staging: wilc1000: linux_wlan_sdio.c: move all the codes to wilc_sdio.c

To Combine linux_wlan_sdio.c and wilc_sdio.c as one file, move all the codes
in linux_wlan_sdio.c to wilc_sdio.c, and make functions static only.
No Modification has not been made except static, just moved them.
Function declaration in linux_wlan_sdio.h is needless, so just remove them.
linux_wlan_sdio.[ch] will be deleted in the next patch.

Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>