libata-scsi: use u8 array to store mode page copy

ata_mselect_*() would initialize a char array for storing a copy of
the current mode page. However, char could be signed char. In that
case, bytes larger than 127 would be converted to negative number.

For example, 0xff from def_control_mpage[] would become -1. This
prevented ata_mselect_control() from working at all, since when it
did the read-only bits check, there would always be a mismatch.

Signed-off-by: Tom Yan <[e-mail]>
Signed-off-by: Tejun Heo <[e-mail]>

drivers/ata/libata-scsi.c

···
 {
 	struct ata_taskfile *tf = &qc->tf;
 	struct ata_device *dev = qc->dev;
-	char mpage[CACHE_MPAGE_LEN];
+	u8 mpage[CACHE_MPAGE_LEN];
 	u8 wce;
 	int i;
 
···
 			       const u8 *buf, int len, u16 *fp)
 {
 	struct ata_device *dev = qc->dev;
-	char mpage[CONTROL_MPAGE_LEN];
+	u8 mpage[CONTROL_MPAGE_LEN];
 	u8 d_sense;
 	int i;