servo_v4: add command ada_srccaps to list adapter's SrcCap
servo_v4: add command ada_srccaps to list adapter's SrcCap

Add the command for a new servod control.
FAFT tests can be aware of the capability of the adapter on servo_v4.

BUG=b:140256624
BRANCH=servo_v4
TEST=ensure the command print all the SrcCap
     > ada_srccaps
     0: 5000mV/3000mA
     1: 9000mV/3000mA
     2: 10000mV/3000mA
     3: 12000mV/3000mA
     4: 15000mV/3000mA
     5: 20000mV/3000mA

Change-Id: I5d08240f87838267464a38fa09ab2ee59c7d4edf
Signed-off-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2055267
Reviewed-by: Jett Rink <9d4aef0593e6843318d99df31597fb6153b89787@chromium.org>
Reviewed-by: Wai-Hong Tam <04b587fdf5845741a0c5a8b9cd59ca72d73ef8fc@google.com>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec