uboot-imx

fpga: Change the first parameter in fpga_loadbitstream

All fpga functions use devnum as int. Only fpga_loadbitstream
is using it as unsinged long dev.
This patch synchronize it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Tom Rini <trini@ti.com>