Reorganisation of NUCLEO_L053R8 and DISCO_L053C8 cmsis folders  

Same reorganisation as @bcostm suggested in #630 for the targets NUCLEO_L053R8 and DISCO_L053C8.

In #617 rosterloh used a slightly newer version of the STM32Cube driver for DISCO_L053C8. With this reorganistion both targets are using the same, newer version.