arm64: Move cpu_resume into the text section

The function cpu_resume currently lives in the .data
section. This breaks functionality to make .data no
execute. Move cpu_resume to .text which is where it
actually belongs.

Change-Id: I1919237f54ff268b62aa48ac664152e80faf7126
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>