[ARM] 3484/1: Correct AEABI CFLAGS for correct enum handling

Patch from Richard Purdie

The AAPCS says that enums can be variably sized depending on the range
of valid values. This is not the accepted behaviour under linux so for
compatibility gcc has an aapcs-linux target, the main difference being
that enums are always of type int. Change the ARM Makefile to use this
target.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>