CRISv32: ETRAXFS: Fix recursive spinlock

Move pinmux alloc/dealloc code into functions that don't take
the spinlock so we can use from code that has the spinlock already.

CRISv32 has no working SMP, so spinlocks becomes a NOP,
so deadlock was never seen.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>