drm/amdkfd: replace err by dbg print at svm vram migration

Avoid spam the kernel log on application memory allocation failures.
__func__ argument was also removed from dev_fmt macro due to
parameter conflicts with dynamic_dev_dbg.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.comi>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>