drm/i915/gt: Avoid uninitialized use of rpcurupei in frequency_show

When building with clang + -Wuninitialized:

drivers/gpu/drm/i915/gt/debugfs_gt_pm.c:407:7: warning: variable
'rpcurupei' is uninitialized when used here [-Wuninitialized]
                           rpcurupei,
                           ^~~~~~~~~
drivers/gpu/drm/i915/gt/debugfs_gt_pm.c:304:16: note: initialize the
variable 'rpcurupei' to silence this warning
                u32 rpcurupei, rpcurup, rpprevup;
                             ^
                              = 0
1 warning generated.

rpupei is assigned twice; based on the second argument to
intel_uncore_read, it seems this one should have been assigned to
rpcurupei.

Fixes: 9c87855 ("drm/i915/gt: Use the RPM config register to determine clk frequencies")
Link: ClangBuiltLinux/linux#1016
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200429030051.920203-1-natechancellor@gmail.com

drivers/gpu/drm/i915/gt/debugfs_gt_pm.c

@@ -336,7 +336,7 @@ static int frequency_show(struct seq_file *m, void *unused)
 		rpdeclimit = intel_uncore_read(uncore, GEN6_RP_DOWN_THRESHOLD);
 
 		rpstat = intel_uncore_read(uncore, GEN6_RPSTAT1);
-		rpupei = intel_uncore_read(uncore, GEN6_RP_CUR_UP_EI) & GEN6_CURICONT_MASK;
+		rpcurupei = intel_uncore_read(uncore, GEN6_RP_CUR_UP_EI) & GEN6_CURICONT_MASK;
 		rpcurup = intel_uncore_read(uncore, GEN6_RP_CUR_UP) & GEN6_CURBSYTAVG_MASK;
 		rpprevup = intel_uncore_read(uncore, GEN6_RP_PREV_UP) & GEN6_CURBSYTAVG_MASK;
 		rpcurdownei = intel_uncore_read(uncore, GEN6_RP_CUR_DOWN_EI) & GEN6_CURIAVG_MASK;