phy: omap-usb2: fix devm_ioremap_resource error detection code

devm_ioremap_resource returns an ERR_PTR value, not NULL, on failure.

A simplified version of the semantic match that finds this problem is as
follows:

// <smpl>
@@
expression e,e1;
statement S;
@@

*e = devm_ioremap_resource(...);
if (!e1) S

// </smpl>

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>