Patch from Lennert Buytenhek

On armv4t systems, we have always compiled the kernel with -march=armv4
instead of -march=armv4t, which means that any use of bx will bomb out.

Commit ba9b5d76 introduced the use of
bx in the kernel, which means we need to compile with -march=armv4t on
armv4t systems now.
Signed-off-by: NLennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>