arch/arm/plat-omap: Drop an unnecessary NULL test

map_iovm_area is only called from a context where its second argument is
known not to be NULL, so drop the unnecessary test.  If new could be NULL,
the initialization of da should be moved below the test.

A simplified version of the semantic match that detects this problem is as
follows (http://coccinelle.lip6.fr/

):

// <smpl>
@match exists@
expression x, E;
identifier fld;
@@

* x->fld
  ... when != \(x = E\|&x\)
* x == NULL
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>