bus: omap: add MODULE_LICENSE tags

linux-4.15 warns about missing MODULE_LICENSE tags such as these

WARNING: modpost: missing MODULE_LICENSE() in drivers/bus/omap_l3_noc.o
WARNING: modpost: missing MODULE_LICENSE() in drivers/bus/omap_l3_smx.o

For completeness, I'm also adding MODULE_AUTHOR and MODULE_DESCRIPTION
tags, but I decided to leave out the email addresses, as all three
authors are working for other companies now.

Cc: Sricharan R <sricharan@codeaurora.org>
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Olof Johansson <olof@lixom.net>