vp9-svc: Fix issue with svc resize and aq_mode=3

Fix crash for dynamic resize with cyclic refresh (aq_mode=3)
and spatial layers. Issue happens when the encoder is resized
to a larger resolution while aq_mode is disabled (0).
When this resize happens the re-allocation for the svc layer
context buffers (specific to cyclic refresh) was not being done
because aq_mode was not enabled.

Fix is to remove the conditional check on aq_mode within
the reallocation block of vp9_change_config().

Unittest added.

Bug: 526717473

Change-Id: I10478f6a63340aba411b40384939b2056c5bd268