broadcom/vc5: Pack clear colors according to the TLB internal format/type.

broadcom/vc5: Pack clear colors according to the TLB internal format/type.

The previous packing I did got us all the R*16F and R*32F formats, where
the pipe format basically matched the TLB's format, but since the clear
color will just be memcpyed to the TLB, we should be looking at its format
for deciding how to pack.

Fixes RGB565, RGB5_A1 and RGBA10 fbo-clear-formats tests and improves
4444.