Bluetooth: btintel: Refactor btintel_set_ppag()

Current flow iterates the ACPI table associated with Bluetooth
controller looking for PPAG method. Method name can be directly passed
to acpi_evaluate_object function instead of iterating the table.

Fixes: c585a92b ("Bluetooth: btintel: Set Per Platform Antenna Gain(PPAG)")
Signed-off-by: Kiran K <kiran.k@intel.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>