net: encx24j600: Add parentheses to fix precedence

In functions regmap_encx24j600_phy_reg_read() and
regmap_encx24j600_phy_reg_write() in the conditions of the waiting
cycles for filling the variable 'ret' it is necessary to add parentheses
to prevent wrong assignment due to logical operations precedence.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d70e5326

 ("net: Microchip encx24j600 driver")
Signed-off-by: Valentina Goncharenko <goncharenko.vp@ispras.ru>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>