mtd: suppress warnings in inline_map_read()

With gcc 4.4.3 -O2 on MIPS32:

drivers/mtd/chips/cfi_util.c: In function 'cfi_qry_present':
include/linux/mtd/map.h:390: warning: 'r' may be used uninitialized in this function
include/linux/mtd/map.h:375: note: 'r' was declared here
include/linux/mtd/map.h:390: warning: 'r' may be used uninitialized in this function
include/linux/mtd/map.h:375: note: 'r' was declared here

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>