powerpc/85xx: Get twr_p102x to compile again

With CONFIG_QUICC_ENGINE enabled and CONFIG_UCC_GETH + CONFIG_SERIAL_QE
disabled we have an unused variable (np). The code won't compile with
-Werror.

Move the np variable to the block where it is actually used.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Scott Wood <oss@buserror.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191219151602.1908411-1-bigeasy@linutronix.de