media: atomisp: Fix alloc_pages_bulk() failed errors

media: atomisp: Fix alloc_pages_bulk() failed errors

Systems with the atomisp ISP do not have a lot of memory for modern
standards, so these are often under memory pressure and alloc_pages_bulk()
does not try very hard to free pages before returning an amount of pages
which is less then requested. This leads to streaming from the camera
often failing with a "alloc_pages_bulk() failed" error.

vmalloc() also uses alloc_pages_bulk(), but falls back to allocating one
page at a time when that fails.

Do the same in alloc_private_pages() to avoid these errors.

While at it also drop the weird custom GFP flags and just use GFP_KERNEL
and drop the dev_err() as alloc_pages() already complaints loudly if
it fails itself.

Closes: https://github.com/jfwells/linux-asus-t100ta/issues/4
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>