net: dsa: mv88e6xxx: refactor mv88e6352_g1_reset

The new mv88e6250_g1_reset() is identical to mv88e6352_g1_reset() except
for the call of mv88e6352_g1_wait_ppu_polling(), so refactor the 6352
version in term of the 6250 one. No functional change.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>