drivers: bluetooth: hci: Remove config BT_SPI_BLUENRG

Remove BT_SPI_BLUENRG Kconfig parameter as it is redundant according to
the new changes introduced by ST SPI protocol V1 and V2.

Remove "config BT_SPI_BLUENRG" from the boards that were using it.

Signed-off-by: Ali Hozhabri <ali.hozhabri@st.com>