Bluetooth: host: Fix size of L2CAP disconnect request pool
Bluetooth: host: Fix size of L2CAP disconnect request pool

Fix size of L2CAP disconnect request buffer pool which did not include
the size of the L2CAP signal header.

Regression from: 3346aa4d39bd2b0ed11ecbad6556affb8cea1569

Signed-off-by: Joakim Andersson <cf0fcab5d38d6e132e92a97bcb0bae257abf4936@nordicsemi.no>

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