drivers/i2c: remove !S390 dependency, add missing GENERIC_HARDIRQS dependencies

Remove !S390 dependency from i2c Kconfig, since s390 now supports PCI, HAS_IOMEM
and HAS_DMA, however we need to add a couple of GENERIC_HARDIRQS dependecies to
fix compile and link errors like these:

ERROR: "devm_request_threaded_irq" [drivers/i2c/i2c-smbus.ko] undefined!
ERROR: "devm_request_threaded_irq" [drivers/i2c/busses/i2c-ocores.ko] undefined!

Cc: Wolfram Sang <w.sang@pengutronix.de>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>