char: mware: fix returnvar.cocci warnings

Remove unneeded variables when "0" can be returned.

Generated by: scripts/coccinelle/misc/returnvar.cocci
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: jing yangyang <jing.yangyang@zte.com.cn>
Link: https://lore.kernel.org/r/20210820021752.10927-1-jing.yangyang@zte.com.cnSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/mwave/tp3780i.c

@@ -470,8 +470,6 @@ int tp3780I_StartDSP(THINKPAD_BD_DATA * pBDData)
 
 int tp3780I_QueryAbilities(THINKPAD_BD_DATA * pBDData, MW_ABILITIES * pAbilities)
 {
-	int retval = 0;
-
 	PRINTK_2(TRACE_TP3780I,
 		"tp3780i::tp3780I_QueryAbilities entry pBDData %p\n", pBDData);
 
@@ -502,7 +500,7 @@ int tp3780I_QueryAbilities(THINKPAD_BD_DATA * pBDData, MW_ABILITIES * pAbilities
 	PRINTK_1(TRACE_TP3780I,
 		"tp3780i::tp3780I_QueryAbilities exit retval=SUCCESSFUL\n");
 
-	return retval;
+	return 0;
 }
 
 int tp3780I_ReadWriteDspDStore(THINKPAD_BD_DATA * pBDData, unsigned int uOpcode,