add option to de-activate EC console input when WP is on
add option to de-activate EC console input when WP is on

With a Toad cable, the user can access the EC serial console through the
micro-B connector.
We probably need to de-activate the input on the EC serial console when
the Write-Protect is on, since we have fairly "powerful" commands on the
EC command-line.
Add a new CONFIG_CONSOLE_RESTRICTED_INPUT on platforms with externally
accessible EC serial port.

Signed-off-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

BRANCH=spring
BUG=chrome-os-partner:18716
TEST=on Spring with CONFIG_CONSOLE_RESTRICTED_INPUT set, try with and without
write-protect, use successfully the EC console in the former case, and see
"Console is DISABLED" in the latter case.

Change-Id: Ic9646d5468183f4d8f94b5e5e1d2a727941d7bbe
Reviewed-on: https://gerrit.chromium.org/gerrit/49537
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>
Tested-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>
Commit-Queue: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

thehobn/ec,fourier49/BZ_DEV_EC,mtk09422/chromiumos-platform-ec,akappy7/ChromeOS_EC_LED_Diagnostics,thehobn/ec,coreboot/chrome-ec,md5555/ec,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BZ_DEV_EC,akappy7/ChromeOS_EC_LED_Diagnostics,mtk09422/chromiumos-platform-ec,fourier49/BZ_DEV_EC,gelraen/cros-ec,coreboot/chrome-ec,coreboot/chrome-ec,thehobn/ec,alterapraxisptyltd/chromium-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,longsleep/ec,gelraen/cros-ec,alterapraxisptyltd/chromium-ec,coreboot/chrome-ec,longsleep/ec,gelraen/cros-ec,md5555/ec,md5555/ec,eatbyte/chromium-ec,md5555/ec,alterapraxisptyltd/chromium-ec,longsleep/ec,fourier49/BIZ_EC,fourier49/BIZ_EC,eatbyte/chromium-ec,coreboot/chrome-ec,fourier49/BIZ_EC,thehobn/ec,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BIZ_EC,mtk09422/chromiumos-platform-ec,alterapraxisptyltd/chromium-ec,eatbyte/chromium-ec,eatbyte/chromium-ec,gelraen/cros-ec,longsleep/ec,fourier49/BZ_DEV_EC,mtk09422/chromiumos-platform-ec