av1_loop_restoration_filter_frame: Remove assert.
av1_loop_restoration_filter_frame: Remove assert.

We disable loop restoration when lossless frame is explicitly requested.
But rate control in the encoder may implicitly decide to encode a frame
as lossless too (with base_qindex == 0), in which case we do NOT disable
loop restoration.

Hence, the earlier assertion wasn't always true.

BUG=aomedia:1635

Change-Id: Id77c7866b85a998fafc87e2e6c00ded9c2d2019c

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom