etnaviv: uniform limit update
Current code in etnaviv_screen.c assumes a max number of 168 VS and 64 PS uniforms for all GPUs < GC4000. This is not actually true. GC2000+ has 320 uniforms in total, up to 256 are usable as VS uniforms. Real limits can be found in gcmCONFIGUREUNIFORMS in the Vivante kernel driver file drivers/mxc/gpu-viv/hal/kernel/inc/gc_hal_base.h.
The current number of 64 PS uniforms will prevent some of the more complex QT5 shaders to be compiled successfully.