disk: part: implement generic function part_get_info_by_name()

So far partition search by name has been supported only on the EFI partition
table. This patch extends the search to all partition tables.

Rename part_get_info_efi_by_name() to part_get_info_by_name(), move it from
part_efi.c into part.c and make it a generic function which traverses all part
drivers and searches all partitions (in the order given by the linked list).

For this a new variable struct part_driver.max_entries is added, which limits
the number of partitions searched. For EFI this was GPT_ENTRY_NUMBERS.
Similarly the limit is defined for DOS, ISO, MAC and AMIGA partition tables.

Signed-off-by: Petr Kulhavy <brain@jikos.cz>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Steve Rae <steve.rae@raedomain.com>

disk/part_mac.c

@@ -239,6 +239,7 @@ static int part_get_info_mac(struct blk_desc *dev_desc, int part,
 U_BOOT_PART_TYPE(mac) = {
 	.name		= "MAC",
 	.part_type	= PART_TYPE_MAC,
+	.max_entries	= MAC_ENTRY_NUMBERS,
 	.get_info	= part_get_info_mac,
 	.print		= part_print_mac,
 	.test		= part_test_mac,