npcx: lpc: Remove unsupport old-style host command.
npcx: lpc: Remove unsupport old-style host command.

Since ec doesn't support old-style host command, this CL removes
unsupported parts in npcx's lpc driver and lets the hand-shaking
mechanism between host and ec as easy as possible. It makes sure only
following conditions that ec can clear processing bit of host command.

1. Received LRESET signal.
2. In lpc_init() initialization function caused by sysjump.
3. If command is valid, it will be cleared in lpc_send_response_packet()
   called by host command task.
4. If command is invalid, it will be cleared in lpc_send_response()
   after the response package is ready.

BRANCH=none
BUG=chrome-os-partner:34346
TEST=make BOARD=wheatley; do stress test on wheatley.

Change-Id: I53d17fd9e09b7fb080e4bf71437392bf43db6258
Signed-off-by: Mulin Chao <6bbc5af053a1dfdc363be6857f30de4ac3bcbd16@nuvoton.com>
Reviewed-on: https://chromium-review.googlesource.com/422707
Reviewed-by: Aaron Durbin <af0622ab041e8b0f8e5819838dcc93898196e71f@chromium.org>
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>

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