Patch from Catalin Marinas

The new EABI gcc adds -mthumb-interwork by default, even if
-mabi=apcs-gnu is passed. This causes a warning for every compiled C
file when -march=armv4 is used. The patch adds -mno-thumb-interwork
if the option is supported. This is also useful since we don't need
any ARM/Thumb interworking in the kernel
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>