mcux: flexcan: fixes the race condition

Since the FLEXCAN_TransferSendNonBlocking() function has
read-modify-write operations on global resources, then
if interrupts are enabled and/or if there is more than
one thread with a different priority, threads with
a lower priority can overwrite global resource changes
made by higher priority threads.
Fixes #52673.

Signed-off-by: Mikhail Siomin <victorovich.01@mail.ru>