cpufreq/amd-pstate: Call amd_pstate_set_driver() in amd_pstate_register_driver()

Replace a similar chunk of code in amd_pstate_register_driver() with
amd_pstate_set_driver() call.

Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20241017100528.300143-3-Dhananjay.Ugwekar@amd.com


Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>