i2c: mxc: Print hex instead of decimal for bus address

Better to print the hex value for bus address instead of
decimal, for more readbility on bus addressing.

Before:
------
U-Boot> i2c dev 1
Setting bus to 1
i2c bus 1 at 35274752, no gpio pinctrl state.

After:
------
U-Boot> i2c dev 1
Setting bus to 1
i2c bus 1 at 0x21a4000, no gpio pinctrl state.

Cc: Simon Glass <sjg@chromium.org>
Cc: Heiko Schocher <hs@denx.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Heiko Schocher <hs@denx.de>