uio: fix vma io range check in mmap

the vma range size is always page size aligned in mmap, while the
real io space range may not be page aligned, thus leading to range
check failure in the uio_mmap_physical().

for example, in a case of io range size "mem->size == 1KB", and we
have (vma->vm_end - vma->vm_start) == 4KB, due to "len" is aligned
to page size in do_mmap_pgoff().

now fix this issue by align mem->size to page size in the check.

Signed-off-by: Bin Wang <binw@marvell.com>
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>