drm/radeon: use true,false for bool variable in r100.c

Fixes coccicheck warning:

drivers/gpu/drm/radeon/r100.c:1826:3-31: WARNING: Assignment of 0/1 to bool variable
drivers/gpu/drm/radeon/r100.c:1828:3-31: WARNING: Assignment of 0/1 to bool variable
drivers/gpu/drm/radeon/r100.c:2390:2-22: WARNING: Assignment of 0/1 to bool variable
drivers/gpu/drm/radeon/r100.c:2395:2-22: WARNING: Assignment of 0/1 to bool variable

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>