Decrease the number of pointer derefs in drivers/serial/jsm/jsm_tty.c

Benefits of the patch:
 - Fewer pointer dereferences should make the code slightly faster.
 - Size of generated code is smaller
 - Improved readability
Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com>
Acked-by: N"V. ANANDA KRISHNAN" <mansarov@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>