kernel: i2c: Drop mentioning power management from the smbus slide

I don't want to revert the commit because I think it still improves the
definition by mentioning register-like interface, which is just our
biased observation of the "command" interface (there is no register
register read/write definition in the spec).

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

slides/kernel-i2c/kernel-i2c.tex

@@ -359,9 +359,8 @@ \section{Introduction to the I2C subsystem}
 \begin{frame}{SMBus calls}
   \begin{itemize}
   \item SMBus is a subset of the I2C protocol.
-  \item It focuses on devices power management and defines a standard
-    set of transactions, such as reading/writing from a register-like
-    interface.
+  \item It defines a standard set of transactions, such as
+    reading/writing from a register-like interface.
   \item Linux provides SMBus functions that should preferably be used
     instead of the raw API with devices supporting SMBus.
   \item Such a driver will be usable with both SMBus and I2C adapters