arch/arm/configs/zynq_xcomm_adv7511_defconfig: increase kernel log buf

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Merge branch 'xcomm_zynq_new_pcore_regmap' of https://github.com/analogdevicesinc/linux into xcomm_zynq_new_pcore_regmap