radv/radeonsi: Don't count read-only data when reporting code size

radv/radeonsi: Don't count read-only data when reporting code size

We usually use these counts as a simple way to figure out if a change
reduces the number of instructions or shrinks an instruction. However,
since .rodata sections aren't executed, we shouldn't be counting their
size for this analysis. Make the linker return the total executable
size, and use it to report the more useful size in both drivers.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>