amdkfd: Introduce kfd_create_process_sysfs as a separate function

amdkfd: Introduce kfd_create_process_sysfs as a separate function

KFD creates sysfs entries for a kfd_process in
function kfd_create_process when creating it.

This commit extracts the code creating sysfs
entries to a separate function because it
would be invoked in other code path like
creating secondary kfd contexts (kfd_process).

Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>