i2c/isp1301_omap: Build fix

Build fix to the isp1301_omap driver ... this driver gets built
more often in the OMAP tree than in mainline, partly because the
defconfig for H2 (plus probably H3 and H4) needs updating.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>