drm: bridge/dw_hdmi: fix register I2CM_ADDRESS register name

I2CM_ADDRESS became a MESS, fix it, also change guarding define
to __DW_HDMI_H__ , since the driver is not IMX specific.

Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>