drm/i915/hwmon: Replace hwm_field_scale_and_write with hwm_power_max_write

hwm_field_scale_and_write has a single caller hwm_power_write and is
specific to hwm_power_write but makes it appear that it is a general
function which can have multiple callers. Replace the function with
hwm_power_max_write which is specific to hwm_power_write and use that in
future patches where the function needs to be extended.

Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230216164944.2366150-2-ashutosh.dixit@intel.com