mb/purism/librem_mini: Increase TDP/PL2 setting

PL2 was set artificially low during development when the active cooling
fan was not functional, and never corrected once the fan was fixed.
Raise PL2 to a value which works with both Librem Mini variants.

Change-Id: Ie377392020f73359aed80ddae727adb6f8d06344
Signed-off-by: Matt DeVillier <matt.devillier@puri.sm>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47186
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>

src/mainboard/purism/librem_cnl/variants/librem_mini/devicetree.cb

@@ -8,7 +8,7 @@ chip soc/intel/cannonlake
 	# Power limit
 	register "power_limits_config" = "{
 		.tdp_pl1_override = 25,
-		.tdp_pl2_override = 28,
+		.tdp_pl2_override = 51,
 	}"
 
 	# Enable Enhanced Intel SpeedStep