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/include/cros_ec.h b/include/cros_ec.h
index 3166132..1199d92 100644
--- a/include/cros_ec.h
+++ b/include/cros_ec.h
@@ -33,7 +33,7 @@
 	unsigned int bus_num;		/* Bus number (for I2C) */
 	unsigned int max_frequency;	/* Maximum interface frequency */
 	struct fdt_gpio_state ec_int;	/* GPIO used as EC interrupt line */
-	int cmd_version_is_supported;   /* Device supports command versions */
+	int protocol_version;           /* Protocol version to use */
 	int optimise_flash_write;	/* Don't write erased flash blocks */
 
 	/*
@@ -260,8 +260,7 @@
  * Check whether the LPC interface supports new-style commands.
  *
  * LPC has its own way of doing this, which involves checking LPC values
- * visible to the host. Do this, and update dev->cmd_version_is_supported
- * accordingly.
+ * visible to the host. Do this, and update dev->protocol_version accordingly.
  *
  * @param dev		CROS-EC device to check
  */