nuc: enable CLKRUN functionality for SERIRQ quiet mode.
nuc: enable CLKRUN functionality for SERIRQ quiet mode.

Set alternative pin from GPIO to CLKRUN if SERIRQ is under quiet mode
Once we need LCLK, CLKRUN will pull low automatically.

Modified drivers:
1. lpc.c.: enable CLKRUN functionality for SERIRQ no matter continuous or
quiet mode.

BUG=chrome-os-partner:34346
TEST=make buildall -j; test nuvoton IC specific drivers
BRANCH=none

Change-Id: I58b11340833b26bc64bfe499272fd3b319b33202
Signed-off-by: CHLin <49997681dc186e71092740314bf6c6feeca6e227@nuvoton.com>
Reviewed-on: https://chromium-review.googlesource.com/314971
Commit-Ready: CH Lin <49997681dc186e71092740314bf6c6feeca6e227@nuvoton.com>
Tested-by: CH Lin <49997681dc186e71092740314bf6c6feeca6e227@nuvoton.com>
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>

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