net: phy: micrel: Fix incorrect variable type in micrel

In lanphy_read_page_reg, calling __phy_read() might return a negative
error code. Use 'int' to check the error code.

Fixes: 7c2dcfa2 ("net: phy: micrel: Add support for LAN8804 PHY")
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220509144519.2343399-1-wanjiabing@vivo.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>