tools: ffs-aio-example: fix header values endianess

We wrap numeric values of fs_count and hs_count fields in htole32,
because they should be in little-endian format.

Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>