ultrahdr: Add lower bounds to input resolution to avoid empty jpeg image

If the test image is 2x2, then gain map size is 0x0, which causes
problems during gainmap compression. Add lower bounds to supported
resolution.

Bug: 283500706
Test: ./libultrahdr_test

Change-Id: I761330bcd5cd4506c38d053a479a135eed6c38ac
1 file changed