drm/i915/intel_dsi_vbt: Add support for PMIC MIPI sequences

Add support for PMIC MIPI sequences using the new
intel_soc_pmic_exec_mipi_pmic_seq_element function.

This fixes the DSI LCD panel not lighting up when not initialized by the
GOP (because an external monitor was connected) on GPD win and GPD pocket
devices.

Specifically the LCD panel seems to need GPIO pin 9 on the PMIC to be
driven high, which is done through a PMIC MIPI sequence. Before this commit
if the sequence was not executed by the GOP the pin would stay low causing
the LCD panel to not work. Having the MIPI sequences properly control this
GPIO should also help save some power when the panel is off.

Changes in v2, v3:
-Only changes to other patches in this patch-set

Changes in v4:
-Move decoding of the raw 15 bytes PMIC MIPI sequence element into
 i2c-address, register-address, value and mask into the mipi_exec_pmic()
 function instead of passing the raw data to
 intel_soc_pmic_exec_mipi_pmic_seq_element()

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190107111556.4510-5-hdegoede@redhat.com