remoteproc: Remove unused variable

Warning log:
drivers/remoteproc/zynq_remoteproc.c: In function 'zynq_rproc_start':
drivers/remoteproc/zynq_remoteproc.c:81:27: warning: unused variable
'local' [-Wunused-variable]
  struct zynq_rproc_pdata *local = platform_get_drvdata(pdev);
                           ^

Signed-off-by: Michal Simek <michal.simek@xilinx.com>