staging: rtl8723bs: Fix checkpatch.pl warnings

This patch resolves coding style brace warning and constant on right warning.
WARNING: Comparisons should place the constant on the right side of the test
WARNING: braces {} are not necessary for single statement blocks
CHECK: Comparison to NULL could be written "!pbuf"
Signed-off-by: Vandana BN <bnvandana@gmail.com>
------
 v2- Edited commit message and subject
 v3- Edited commit message
 v4- changed NULL check to use !pbuf
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723bs/core/rtw_debug.c

@@ -1425,9 +1425,8 @@ int proc_get_btcoex_info(struct seq_file *m, void *v)
 	padapter = (struct adapter *)rtw_netdev_priv(dev);
 
 	pbuf = rtw_zmalloc(bufsize);
-	if (NULL == pbuf) {
+	if (!pbuf)
 		return -ENOMEM;
-	}
 
 	rtw_btcoex_DisplayBtCoexInfo(padapter, pbuf, bufsize);