drm/amdkfd: Set svm range max pages

This will be used to split giant svm range into smaller ranges, to
support VRAM overcommitment by giant range and improve GPU retry fault
recover on giant range.

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