staging: wilc1000: rename PendingAcks_arrBase variable

This patch rename the PendingAcks_arrBase variable to pending_base
to avoid CamelCase naming convention.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>