soc/intel/tgl: Add configurable value for ConfigTdpLevel

soc/intel/tgl: Add configurable value for ConfigTdpLevel

According to Tigerlake TDP specifications (doc #575683, table 4-2),
TGL supports different TDP levels depends on CPU segement/package,
IA Cores and graphics configuration. For example, UP3 4-Core GT2
suppots base TDP=28W, Configurable TDP-Down_1=15W and Configurable
TDP-Down_2=12W. This configurable value can be used to select
suitable TDP level

Change-Id: I4242575807caac172b6cbe667839bf6c9241f3c5
Signed-off-by: Derek Huang <derek.huang@intel.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50104
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>