Making code more compliant to CodingStyle, also remove
unneeded goto clauses in twl_init_irq.

goto's will generate extra branch instructions before exiting
from the function; instead, exits earlier to avoid such branch
instructions.
Signed-off-by: Felipe Balbi <felipe.lima@indt.org.br>
Signed-off-by: Tony Lindgren <tony@atomide.com>