Recent changes to nwfpe broke the build with some gcc versions:

In file included from arch/arm/nwfpe/softfloat.c:33:
arch/arm/nwfpe/fpa11.h:32: global register variable follows a function definition
make[1]: *** [arch/arm/nwfpe/softfloat.o] Error 1

Since we now ensure that the kernel stack is empty when returning
to user space, we can now access the userspace registers with
reference to the kernel stack using current_thread_info(), rather
than remembering the stack pointer at the time nwfpe was called.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>