net: dsa: microchip: Fix a link check in ksz9477_pcs_read()

net: dsa: microchip: Fix a link check in ksz9477_pcs_read()

The BMSR_LSTATUS define is 0x4 but the "p->phydev.link" variable
is a 1 bit bitfield in a u32.  Since 4 doesn't fit in 0-1 range
it means that ".link" is always set to false.  Add a !! to fix
this.

[Jakub: According to Maxime the phydev struct isn't really
used and we should consider removing it completely. So not
treating this as a fix.]

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/aQSz_euUg0Ja8ZaH@stanley.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>