drm/amdgpu: Fix GPU TLB update error when PAGE_SIZE > AMDGPU_PAGE_SIZE

When PAGE_SIZE is larger than AMDGPU_PAGE_SIZE, the number of GPU TLB
entries which need to update in amdgpu_map_buffer() should be multiplied
by AMDGPU_GPU_PAGES_IN_CPU_PAGE (PAGE_SIZE / AMDGPU_PAGE_SIZE).

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Yi Li <liyi@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org