disp: msm: add support for variable compression ratios

Currently the compression ratio is hard-coded to either 2:1 or
3:1 in several places. This is not sufficient for new compression
algorithms as they can support higher compression ratios.

Add support for calculating the compression ratios from the source
and target bpp thereby eliminating hard-coding.

Change-Id: I6383f3d0c781193d0a9ed74df5a95d8e856edb3d
Signed-off-by: Abhinav Kumar <abhinavk@codeaurora.org>

msm/sde/sde_encoder_phys.h

@@ -310,7 +310,7 @@ struct sde_encoder_phys {
 	struct sde_hw_intf_cfg intf_cfg;
 	struct sde_hw_intf_cfg_v1 intf_cfg_v1;
 	enum msm_display_compression_type comp_type;
-	enum msm_display_compression_ratio comp_ratio;
+	u32 comp_ratio;
 	u32 dsc_extra_pclk_cycle_cnt;
 	u32 dsc_extra_disp_width;
 	bool wide_bus_en;