WMI: Remove unnecessary null test

This patch removes the null test on block. block is initialized at the
beginning of the function to &wblock->gblock. Since wblock is
dereferenced prior to the null test, wblock must be a valid pointer,
and &wblock->gblock cannot be null.

The following Coccinelle script is used for detecting the change:

@r@
expression e,f;
identifier g,y;
statement S1,S2;
@@

*e = &f->g
<+...
 f->y
 ...+>
*if (e != NULL || ...)
 S1 else S2

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>