partitions: msdos: fix one-byte get_unaligned()

A simplification of get_unaligned() clashes with callers that pass
in a character pointer, causing a harmless warning like:

block/partitions/msdos.c: In function 'msdos_partition':
include/asm-generic/unaligned.h:13:22: warning: 'packed' attribute ignored for field of type 'u8' {aka 'unsigned char'} [-Wattributes]

Remove the SYS_IND() macro with the get_unaligned() call
and just use the ->ind field directly.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>