drm/amd/display: fix minor codestyle problems

Fixes five checkpatch warnings:

CHECK: Please don't use multiple blank lines
+
+

ERROR: Macros with complex values should be enclosed in parentheses
+#define MAX_I64 \
+       (int64_t)((1ULL << 63) - 1)

WARNING: Missing a blank line after declarations
+       struct bw_fixed res;
+       ASSERT(value < BW_FIXED_MAX_I32 && value > BW_FIXED_MIN_I32);

ERROR: that open brace { should be on the previous line
+               do
+               {

ERROR: that open brace { should be on the previous line
+                       if (remainder >= arg2_value)
+                       {

Signed-off-by: Tales Aparecida <tales.aparecida@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>