samples: hci_spi: Add net_buf headroom for hci_spi
samples: hci_spi: Add net_buf headroom for hci_spi

We need 1 byte of headroom for the SPI HCI protocol.
This is not added automatically on the slave side of the SPI connection.

Signed-off-by: Jan Müller <a919ef5a1433eead7f482ba2b6e20cd75463c9fb@nordicsemi.no>

zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr