qr: factor out GFP_ATOMIC to a new structure called qr_settings

The caller can now decide what GFP to use when allocating the
memory needed for the QR library.

A few places remain though, namely:

rscode.c - We will remove this once we migrate to the inkernel
Reed Solomon library.

a WITH_TESTS function in mask.c - WITH_TESTS is not used in the
QR library, will be removed in a future commit

Signed-off-by: Levente Kurusa <levex@linux.com>