[ARM] 3982/2: Explicitly select 32-bit ARM ISA (-marm)

Do not assume that the ARM GCC toolchain defaults to building for the
32-bit ARM ISA (-marm) case. Instead, explicitly select -marm in CFLAGS
since the toolchain default can be for the 16-bit Thumb ISA (-mthumb) in
some odd/rare cases.

Signed-off-by: George G. Davis <gdavis@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>