i2c: bcm-kona: fix inconsistent indenting

smatch rightfully says:
drivers/i2c/busses/i2c-bcm-kona.c:646 bcm_kona_i2c_xfer() warn: inconsistent indenting
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Reviewed-by: Tim Kryger <tim.kryger@gmail.com>