cpufreq/amd-pstate: Call amd_pstate_register() in amd_pstate_init()

Replace a similar chunk of code in amd_pstate_init() with
amd_pstate_register() call.

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20241017100528.300143-2-Dhananjay.Ugwekar@amd.com


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