arm: patch.c : Allow kernel text section to be written

MSM implements CONFIG_RWX and disallows the kernel text to be written.
However, in cases where we temporarily need to write the kernel text,
we explicitly mark it writeable for a short period of time.

Change-Id: I532b663a9bd0115ea5e7177e9dac4ac54e007725
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>