staging: wilc1000: change MAINTAINERS

This patch removes Rachel Kim from the MAINTAINERS list because she
retires from her position and adds Austin shin as new MAINTAINER for
the Atmel wireless link controller: WILC1000 and WILC3000.

Signed-off-by: Tony Cho <tony.cho@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>