drm/nouveau: use nvif_mmu_type to determine BAR1 caching

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvif/device.h

@@ -58,7 +58,6 @@ u64  nvif_device_time(struct nvif_device *);
 #define nvxx_bios(a) nvxx_device(a)->bios
 #define nvxx_fb(a) nvxx_device(a)->fb
 #define nvxx_mmu(a) nvxx_device(a)->mmu
-#define nvxx_bar(a) nvxx_device(a)->bar
 #define nvxx_gpio(a) nvxx_device(a)->gpio
 #define nvxx_clk(a) nvxx_device(a)->clk
 #define nvxx_i2c(a) nvxx_device(a)->i2c