drm/amdgpu/vce1: Check that the GPU address is < 128 MiB

drm/amdgpu/vce1: Check that the GPU address is < 128 MiB

When ensuring the low 32-bit address, make sure it is
less than 128 MiB, otherwise the VCE seems to fail to initialize.
This seems to be an undocumented limitation of the firmware
validation mechanism. Note that in case of VCE1 the BAR
address is zero and we can't change it also due to the
firmware validator.

When programming the mmVCE_VCPU_CACHE_OFFSETn registers,
don't AND them with a mask. This is incorrect because
the register mask is actually 0x0fffffff and useless because
we already ensure the addresses are below the limit.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>