net: marvell.c fix sparse shadowed variable warning

The other if blocks don't redeclare temp, remove the redeclaration in
the final if() block.

drivers/net/phy/marvell.c:214:7: warning: symbol 'temp' shadows an earlier one
drivers/net/phy/marvell.c:160:6: originally declared here

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>