spi: bcm2835: remove use of uninitialized gpio flags variable

Removing the duplicate gpio chip select level handling in
bcm2835_spi_setup() left the lflags variable uninitialized. Avoid trhe
use of such variable by passing default flags to
gpiochip_request_own_desc().

Fixes: 5e31ba0c

 ("spi: bcm2835: fix gpio cs level inversion")
Signed-off-by: Martin Hundebøll <martin@geanix.com>
Link: https://lore.kernel.org/r/20201105090615.620315-1-martin@geanix.com
Signed-off-by: Mark Brown <broonie@kernel.org>