staging: rtl8723bs: hal: Remove NULL check before kfree

NULL check before kfree is unnecessary so remove it.

The following Coccinelle script was used to detect this:
@@ expression E; @@
- if (E != NULL) { kfree(E); }
+ kfree(E);
@@ expression E; @@
- if (E != NULL) { kfree(E); E = NULL; }
+ kfree(E);
+ E = NULL;

Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Link: https://lore.kernel.org/r/20200326132823.GA18625@simran-Inspiron-5558
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>