cassini: use request_firmware

Firmware blob looks like this...
        __le16 load_address
        unsigned char data[]

[akpm@linux-foundation.org: include vmalloc.h]
Signed-off-by: Jaswinder Singh <jaswinder@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>