staging: rts5208: Use array_size() helper in vmalloc() and memset()

The vmalloc() function has no 2-factor argument form, so multiplication
factors need to be wrapped in array_size(). Also, while there, use
array_size() in memset().

This issue was found with the help of Coccinelle and, audited and fixed
manually.

Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Link: https://lore.kernel.org/r/20200616175543.GA28687@embeddedor
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/rts5208/ms.c

···
 		if (!segment->l2p_table)
 			goto BUILD_FAIL;
 	}
-	memset((u8 *)(segment->l2p_table), 0xff, table_size * 2);
+	memset((u8 *)(segment->l2p_table), 0xff, array_size(table_size, 2));
 
 	if (!segment->free_table) {
-		segment->free_table = vmalloc(MS_FREE_TABLE_CNT * 2);
+		segment->free_table = vmalloc(array_size(MS_FREE_TABLE_CNT, 2));
 		if (!segment->free_table)
 			goto BUILD_FAIL;
 	}
-	memset((u8 *)(segment->free_table), 0xff, MS_FREE_TABLE_CNT * 2);
+	memset((u8 *)(segment->free_table), 0xff, array_size(MS_FREE_TABLE_CNT, 2));
 
 	start = (u16)seg_no << 9;
 	end = (u16)(seg_no + 1) << 9;