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>