docs: i2c: call it "I2C" consistently

Uppercase "I2C" is used almost everywhere in the docs, but the lowercase
version "i2c" is used somewhere. Use the uppercase form consistently.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Acked-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/Documentation/i2c/i2c-protocol.rst b/Documentation/i2c/i2c-protocol.rst
index 2f8fcf6..0222c97 100644
--- a/Documentation/i2c/i2c-protocol.rst
+++ b/Documentation/i2c/i2c-protocol.rst
@@ -2,7 +2,7 @@
 I2C Protocol
 ============
 
-This document describes the i2c protocol. Or will, when it is finished :-)
+This document describes the I2C protocol. Or will, when it is finished :-)
 
 Key to symbols
 ==============
@@ -57,7 +57,7 @@
 =====================
 
 The following modifications to the I2C protocol can also be generated by
-setting these flags for i2c messages. With the exception of I2C_M_NOSTART, they
+setting these flags for I2C messages. With the exception of I2C_M_NOSTART, they
 are usually only needed to work around device issues:
 
 I2C_M_IGNORE_NAK: