fs: usbifs: Fix warning in ubifs

This patch fixes the below warning by typecasting it properly
fs/ubifs/ubifs.c: In function 'ubifs_load':
fs/ubifs/ubifs.c:942:29: warning: cast to pointer from integer
of different size [-Wint-to-pointer-cast]
  err = ubifs_read(filename, (void *)addr, 0, size, &actread);

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Heiko Schocher <hs@denx.de>