NFC: st21nfcb: Remove gpio_irq field in static and dts configuration

- phy->gpio_irq is never done out of the request resources.
- irq_of_parse_and_map is already done in the i2c core so client->irq is
already set when entering in st21nfcb_hci_i2c_of_request_resources
- In case of static platform configuration client->irq can be set directly.
- It simplifies the code a bit.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>