Added CAN API support for NUCLEO_F042K6 target.
"stm32f042x6.h" file was changed to avoid compilation errors.
Change-Id: I9622a233775fc6834201a322740bf5026244d50e
Added CAN API support for NUCLEO_F072RB target.
*stm32f072xb.h* file was changed to avoid compilation errors.
Change-Id: I9da75fde29fd19f0326d554acc1dbb5386b08317
Added CAN API suport for NUCLEO_F091RC target.
*stm32f091xc.h* file was changed to avoid compilation errors.
Change-Id: I9207575a0e2ad0f8e3a4bb78eb23d1e7b4a94171