Staging: gdm72xx: Fix incorrect type in assignment in gdm_wimax.c

This patch fixes following sparse warnings:
drivers/staging/gdm72xx/gdm_wimax.c:543:37: warning: incorrect type in argument 1 (different address spaces)
drivers/staging/gdm72xx/gdm_wimax.c:543:37:    expected void [noderef] <asn:1>*to
drivers/staging/gdm72xx/gdm_wimax.c:543:37:    got void *buf
drivers/staging/gdm72xx/gdm_wimax.c:566:41: warning: incorrect type in argument 2 (different address spaces)
drivers/staging/gdm72xx/gdm_wimax.c:566:41:    expected void const [noderef] <asn:1>*from
drivers/staging/gdm72xx/gdm_wimax.c:566:41:    got void *buf

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>