i2c: ocores: use request_any_context_irq() to register IRQ handler

The i2c-ocores device is an HDL component that get instantiated in FPGA.
The software stack used to drive an FPGA can be very different, and the
i2c-ocore ip-core must work in different context. With respect to this
patch the IRQ controller behind this device, and its driver, can have
different implementations (nested threads). For this reason, it is safer
to use `request_any_context_irq()` to avoid errors at probe time.

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>