nvme: Fix potential sign extension issue in nvme_blk_rw()

"lbas" with type "u16" (16 bits, unsigned) is promoted in
"lbas << ns->lba_shift" to type "int" (32 bits, signed), then
sign-extended to type "unsigned long long" (64 bits, unsigned).
If "lbas << ns->lba_shift" is greater than 0x7FFFFFFF, the upper
bits of the result will all be 1.

Fix it by casting "lbas" to "u32".

Reported-by: Coverity (CID: 166730)
Signed-off-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NTom Rini <trini@konsulko.com>

drivers/nvme/nvme.c

@@ -723,7 +723,7 @@ static ulong nvme_blk_rw(struct udevice *udev, lbaint_t blknr,
 				&c, NULL, IO_TIMEOUT);
 		if (status)
 			break;
-		temp_len -= lbas << ns->lba_shift;
+		temp_len -= (u32)lbas << ns->lba_shift;
 		buffer += lbas << ns->lba_shift;
 	}