drm/amdgpu/swsmu/navi1x: Remove unnecessary conversion to bool

Fix the following coccicheck warnings:

./drivers/gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c:900:47-52: WARNING:
conversion to bool not needed here.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>