arm64: mm: restrict EXEC to text and init

If CONFIG_FORCE_PAGES is enabled, DATA and RO is set
as EXEC which cause PAN feature failure. Fix it.

Change-Id: I4486ce34b47f0f1d022a8d783b3474ba0a76dd8c
Signed-off-by: Vishwanath Raju K <vishk@codeaurora.org>