lib: rbtree: Do not use lowercase l for literal suffix
lib: rbtree: Do not use lowercase l for literal suffix

Use suffix L to remove potential ambiguity between digit 1 and letter
l.

MISRA-C rule 7.3

Signed-off-by: Flavio Ceolin <979b9165500b0741b9d0500e2efd74fc1547bff7@intel.com>

finikorg/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,ldts/zephyr,finikorg/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,Vudentz/zephyr,nashif/zephyr,punitvara/zephyr,punitvara/zephyr,galak/zephyr,punitvara/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,ldts/zephyr,galak/zephyr,explora26/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,Vudentz/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,galak/zephyr,ldts/zephyr,Vudentz/zephyr