rtl8150: Use heap buffers for all register access

Allocating USB buffers on the stack is not portable, and no longer
works on x86_64 (with VMAP_STACK enabled as per default).

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
static int read_mii_word(rtl8150_t * dev, u8 phy, __u8 indx, u16 * reg)
{
	int i;
	u8 data[3], tmp;

	data[0] = phy;
	data[1] = data[2] = 0;
	tmp = indx | PHY_READ | PHY_GO;
	i = 0;

	set_registers(dev, PHYADD, sizeof(data), data);
	set_registers(dev, PHYCNT, 1, &tmp);
	do {
		get_registers(dev, PHYCNT, 1, data);
	} while ((data[0] & PHY_GO) && (i++ < MII_TIMEOUT));

	if (i <= MII_TIMEOUT) {
		get_registers(dev, PHYDAT, 2, data);
		*reg = data[0] | (data[1] << 8);
		return 0;
	} else
		return 1;
}

static int read_mii_word(rtl8150_t * dev, u8 phy, __u8 indx, u16 * reg)
{
	int i;
	u8 data[3], tmp;

	data[0] = phy;
	data[1] = data[2] = 0;
	tmp = indx | PHY_READ | PHY_GO;
	i = 0;

	set_registers(dev, PHYADD, sizeof(data), data);
	set_registers(dev, PHYCNT, 1, &tmp);
	do {
		get_registers(dev, PHYCNT, 1, data);
	} while ((data[0] & PHY_GO) && (i++ < MII_TIMEOUT));

	if (i <= MII_TIMEOUT) {
		get_registers(dev, PHYDAT, 2, data);
		*reg = data[0] | (data[1] << 8);
		return 0;
	} else
		return 1;
}
