oak: pd: increase stack size of PDCMD task
oak: pd: increase stack size of PDCMD task

Stack of PDCMD task may be overflow during plug/unplug stree test
with Apple's AV Multiport Adapter. Enlarge the stack size to avoid
system reboot.

BUG=chrome-os-partner:47728
BRANCH=none
TEST=Manual
1.Connect DUT to sink monitor via HDMI dongle.
2.Unplug HDMI USB from DUT side.
3.Plug HDMI USB cable to DUT USB socket.
4.Repeat (Plug and unplug) USB from DUT for 10 times.

Change-Id: Ib6a1fbd0a552b2c6d4656c12554e1306c21adb8a
Signed-off-by: Ben Lok <310171a828df105188e0b545d65d6370e8133283@mediatek.com>
Reviewed-on: https://chromium-review.googlesource.com/315020
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec