arm: fix implicit #include <linux/init.h> in entry asm.

They use the "_INIT" macro and friends, and hence need to
source this header file, vs. relying on getting it implicitly.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>