ARM: dma-mapping: don't allow DMA mappings to be marked executable

DMA mapping permissions were being derived from pgprot_kernel directly
without using PAGE_KERNEL.  This causes them to be marked with executable
permission, which is not what we want.  Fix this.

Change-Id: Ib40f59f3c569f82409943cf8f9a86a9869d922cc
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Git-commit: 0ea1ec713f04bdfac343c9702b21cd3a7c711826
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[lauraa@codeaurora.org: dropped functions not in older builds]
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>