MFD: mcp-sa11x0/assabet: move assabet reset handling out of mcp-sa11x0.c

Move the assabet specific reset handling out of mcp-sa11x0.c, into its
board file.  This leaves the mcp code free from all board specific
details.

Acked-by: Jochen Friedrich <jochen@scram.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>