radeon: r100: Silence 'may be used uninitialized' warnings

  CC [M]  drivers/gpu/drm/radeon/r100.o
In file included from drivers/gpu/drm/radeon/radeon_mode.h:37:0,
                 from drivers/gpu/drm/radeon/radeon.h:80,
                 from drivers/gpu/drm/radeon/r100.c:33:
drivers/gpu/drm/radeon/r100.c: In function 'r100_bandwidth_update':
include/drm/drm_fixed.h:64:13: warning: 'crit_point_ff.full' may be used uninitialized in this function [-Wmaybe-uninitialized]
  u64 tmp = ((u64)A.full << 13);
             ^
drivers/gpu/drm/radeon/r100.c:3153:63: note: 'crit_point_ff.full' was declared here
  fixed20_12 peak_disp_bw, mem_bw, pix_clk, pix_clk2, temp_ff, crit_point_ff;
                                                               ^
drivers/gpu/drm/radeon/r100.c:3583:42: warning: 'disp_drain_rate.full' may be used uninitialized in this function [-Wmaybe-uninitialized]
     temp_ff.full = read_return_rate.full - disp_drain_rate.full;

gcc version 5.3.1 20151219 (Ubuntu 5.3.1-4ubuntu1)

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/r100.c

@@ -3150,7 +3150,8 @@ void r100_bandwidth_update(struct radeon_device *rdev)
 {
 	fixed20_12 trcd_ff, trp_ff, tras_ff, trbs_ff, tcas_ff;
 	fixed20_12 sclk_ff, mclk_ff, sclk_eff_ff, sclk_delay_ff;
-	fixed20_12 peak_disp_bw, mem_bw, pix_clk, pix_clk2, temp_ff, crit_point_ff;
+	fixed20_12 peak_disp_bw, mem_bw, pix_clk, pix_clk2, temp_ff;
+	fixed20_12 crit_point_ff = {0};
 	uint32_t temp, data, mem_trcd, mem_trp, mem_tras;
 	fixed20_12 memtcas_ff[8] = {
 		dfixed_init(1),
@@ -3204,7 +3205,7 @@ void r100_bandwidth_update(struct radeon_device *rdev)
 	fixed20_12 min_mem_eff;
 	fixed20_12 mc_latency_sclk, mc_latency_mclk, k1;
 	fixed20_12 cur_latency_mclk, cur_latency_sclk;
-	fixed20_12 disp_latency, disp_latency_overhead, disp_drain_rate,
+	fixed20_12 disp_latency, disp_latency_overhead, disp_drain_rate = {0},
 		disp_drain_rate2, read_return_rate;
 	fixed20_12 time_disp1_drop_priority;
 	int c;