tools, scripts: refactor error-out statements of Python scripts

In Python, sys.exit() function can also take an object other
than an integer.

If an integer is given to the argument, Python exits with the return
code of it.  If a non-integer argument is given, Python outputs it
to stderr and exits with the return code of 1.

That means,

    print >> sys.stderr, "Blah Blah"
    sys.exit(1)

is equivalent to

    sys.exit("Blah Blah")

The latter is a useful shorthand.

Note:
Some error messages in Buildman and Patman were output to stdout.
But they should go to stderr.  They are also fixed by this commit.
This is a nice side effect.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>

tools/genboardscfg.py

@@ -77,16 +77,14 @@ def check_top_directory():
     """Exit if we are not at the top of source directory."""
     for f in ('README', 'Licenses'):
         if not os.path.exists(f):
-            print >> sys.stderr, 'Please run at the top of source directory.'
-            sys.exit(1)
+            sys.exit('Please run at the top of source directory.')
 
 def get_make_cmd():
     """Get the command name of GNU Make."""
     process = subprocess.Popen([SHOW_GNU_MAKE], stdout=subprocess.PIPE)
     ret = process.communicate()
     if process.returncode:
-        print >> sys.stderr, 'GNU Make not found'
-        sys.exit(1)
+        sys.exit('GNU Make not found')
     return ret[0].rstrip()
 
 ### classes ###
@@ -209,9 +207,7 @@ class DotConfigParser:
         # sanity check of '.config' file
         for field in self.must_fields:
             if not field in fields:
-                print >> sys.stderr, 'Error: %s is not defined in %s' % \
-                                                            (field, defconfig)
-                sys.exit(1)
+                sys.exit('Error: %s is not defined in %s' % (field, defconfig))
 
         # fix-up for aarch64 and tegra
         if fields['arch'] == 'arm' and 'cpu' in fields:
@@ -455,8 +451,7 @@ def __gen_boards_cfg(jobs):
     # wait until the reformat tool finishes
     reformat_process.communicate()
     if reformat_process.returncode != 0:
-        print >> sys.stderr, '"%s" failed' % REFORMAT_CMD[0]
-        sys.exit(1)
+        sys.exit('"%s" failed' % REFORMAT_CMD[0])
 
 def gen_boards_cfg(jobs):
     """Generate boards.cfg file.
@@ -489,8 +484,7 @@ def main():
         try:
             jobs = int(options.jobs)
         except ValueError:
-            print >> sys.stderr, 'Option -j (--jobs) takes a number'
-            sys.exit(1)
+            sys.exit('Option -j (--jobs) takes a number')
     else:
         try:
             jobs = int(subprocess.Popen(['getconf', '_NPROCESSORS_ONLN'],