qr: print_oops: introduce new kernel parameter

Introduce 'qr_oops' core_param so that we can disable the QR printing
if needed.

Signed-off-by: Levente Kurusa <levex@linux.com>
qr: print_oops: don't compress if we don't have a framebuffer

Since compressing and encoding the data makes no sense if we can't
output it later, restructure the function to quickly quit if there
is no framebuffer.

Signed-off-by: Levente Kurusa <levex@linux.com>
qr: print_oops: use memcpy instead of looping

Cleanup some indented empty lines as well.

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