blackfin: portmux: cleanup head file
blackfin: portmux: cleanup head file

drop unused head file
change pinmux request/free macro for backward compatiblity
add function declaration

Signed-off-by: Steven Miao <eb4bb6630d9afd913be5ae87090c50ac1ba7a4b2@gmail.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs