cros_ec: Clean up multiple EC protocol support

Version 1 protocols (without command version) were already no longer
supported in cros_ec.c.  This removes some dead code from the
cros_ec_i2c driver.

Version 2 protcols (with command version) are now called
protocol_version=2, instead of cmd_version_is_supported=1.

A subsequent change will introduce protocol version 3 for SPI.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/misc/cros_ec_spi.c b/drivers/misc/cros_ec_spi.c
index 2fc9110..ef73782 100644
--- a/drivers/misc/cros_ec_spi.c
+++ b/drivers/misc/cros_ec_spi.c
@@ -42,6 +42,12 @@
 	int csum, len;
 	int rv;
 
+	if (dev->protocol_version != 2) {
+		debug("%s: Unsupported EC protcol version %d\n",
+		      __func__, dev->protocol_version);
+		return -1;
+	}
+
 	/*
 	 * Sanity-check input size to make sure it plus transaction overhead
 	 * fits in the internal device buffer.