mb/google/nissa/var/joxer: Configure Acoustic noise mitigation

- Enable Acoustic noise mitigation
- Set slow slew rate VCCIA and VCCGT to SLEW_FAST_8
- Set FastPkgCRampDisable VCCIA and VCCGT to 1

BUG=b:303533832
TEST=USE="project_joxer emerge-nissa coreboot"

Signed-off-by: Mark Hsieh <mark_hsieh@wistron.corp-partner.google.com>
Change-Id: I575da55b96bf4deacec5c0992eae9930eb0745d6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78256
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Derek Huang <derekhuang@google.com>

src/mainboard/google/brya/variants/joxer/overridetree.cb

@@ -16,6 +16,13 @@ end
 chip soc/intel/alderlake
 	register "sagv" = "SaGv_Enabled"
 
+	# Acoustic settings
+	register "acoustic_noise_mitigation" = "1"
+	register "slow_slew_rate[VR_DOMAIN_IA]" = "SLEW_FAST_8"
+	register "slow_slew_rate[VR_DOMAIN_GT]" = "SLEW_FAST_8"
+	register "fast_pkg_c_ramp_disable[VR_DOMAIN_IA]" = "1"
+	register "fast_pkg_c_ramp_disable[VR_DOMAIN_GT]" = "1"
+
 	# EMMC Tx CMD Delay
 	# Refer to EDS-Vol2-42.3.7.
 	# [14:8] steps of delay for DDR mode, each 125ps, range: 0 - 39.