ARM: 7755/1: handle user space mapped pages in flush_kernel_dcache_page

ARM: 7755/1: handle user space mapped pages in flush_kernel_dcache_page

Commit f8b63c1 made flush_kernel_dcache_page a no-op assuming that
the pages it needs to handle are kernel mapped only.  However, for
example when doing direct I/O, pages with user space mappings may
occur.

Thus, continue to do lazy flushing if there are no user space
mappings.  Otherwise, flush the kernel cache lines directly.

Signed-off-by: Simon Baatz <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Cc: <[email protected]> # 3.2+
Signed-off-by: Russell King <[email protected]>