cros_ec: Make cros_ec an explicit drv target

This sets the path to remove some layering violations in internal.c
and make cros_ec entry-point explicit like every other Flashrom drv.

BUG=b:169587323,b:152922794
BRANCH=none
TEST=builds && flashrom -p google_ec:type=fp --flash-name works.

Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Change-Id: If500ecfd5cd2385e6857f2a2aa16e23a4c85d43b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashrom/+/2438178
Tested-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Sam McNally <sammc@chromium.org>
Commit-Queue: Edward O'Callaghan <quasisec@chromium.org>
Auto-Submit: Edward O'Callaghan <quasisec@chromium.org>
diff --git a/programmer.h b/programmer.h
index 0f58eb9..606b095 100644
--- a/programmer.h
+++ b/programmer.h
@@ -94,6 +94,9 @@
 #if CONFIG_REALTEK_MST_I2C_SPI == 1
 	PROGRAMMER_REALTEK_MST_I2C_SPI,
 #endif
+#if CONFIG_GOOGLE_EC == 1
+	PROGRAMMER_GOOGLE_EC,
+#endif
 	PROGRAMMER_INVALID /* This must always be the last entry. */
 };