drm/amdkfd: Use resource_size() helper function

[ Upstream commit 9d086e0d ]

Use the resource_size() function instead of a open coded computation
resource size. It makes the code more readable.

Issue identified using resource_size.cocci coccinelle semantic patch.

Signed-off-by: Deepak R Varma <drv@mailo.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Stable-dep-of: 02eed83a ("drm/amdkfd: fixes for HMM mem allocation")
Signed-off-by: Sasha Levin <sashal@kernel.org>