Fix below warnings happening for xilinx_zynqmp_ep_defconfig

drivers/net/zynq_gem.c: In function ‘zynq_gem_init’:
drivers/net/zynq_gem.c:330:7: warning: cast from pointer to integer
of different size [-Wpointer-to-int-cast]
      ((u32)(priv->rxbuffers) +
       ^
In file included from drivers/net/zynq_gem.c:19:0:
drivers/net/zynq_gem.c:336:10: warning: cast from pointer to integer
of different size [-Wpointer-to-int-cast]
   writel((u32)priv->rx_bd, &regs->rxqbase);
          ^
./arch/arm/include/asm/io.h:146:34: note: in definition of macro ‘writel’
 #define writel(v,c) ({ u32 __v = v; __iowmb(); __arch_putl(__v,c); __v; })
                                  ^
drivers/net/zynq_gem.c: In function ‘zynq_gem_send’:
drivers/net/zynq_gem.c:399:9: warning: cast from pointer to integer
of different size [-Wpointer-to-int-cast]
  writel((u32)priv->tx_bd, &regs->txqbase);
         ^
./arch/arm/include/asm/io.h:146:34: note: in definition of macro ‘writel’
 #define writel(v,c) ({ u32 __v = v; __iowmb(); __arch_putl(__v,c); __v; })
                                  ^
drivers/net/zynq_gem.c:404:22: warning: cast from pointer to integer
of different size [-Wpointer-to-int-cast]
  priv->tx_bd->addr = (u32)ptr;
                      ^
drivers/net/zynq_gem.c:409:9: warning: cast from pointer to integer
of different size [-Wpointer-to-int-cast]
  addr = (u32) ptr;
         ^
drivers/net/zynq_gem.c:414:9: warning: cast from pointer to integer
of different size [-Wpointer-to-int-cast]
  addr = (u32)priv->rxbuffers;
         ^
drivers/net/zynq_gem.c: In function ‘zynq_gem_recv’:
drivers/net/zynq_gem.c:454:31: warning: cast to pointer from integer
of different size [-Wint-to-pointer-cast]
   net_process_received_packet((u8 *)addr, frame_len);
                               ^
drivers/net/zynq_gem.c: In function ‘zynq_gem_initialize’:
drivers/net/zynq_gem.c:533:35: warning: cast from pointer to integer
of different size [-Wpointer-to-int-cast]
  priv->rx_bd = (struct emac_bd *)((u32)bd_space + BD_SEPRN_SPACE);
                                   ^
drivers/net/zynq_gem.c:533:16: warning: cast to pointer from integer
of different size [-Wint-to-pointer-cast]
  priv->rx_bd = (struct emac_bd *)((u32)bd_space + BD_SEPRN_SPACE);

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>