staging: most: rename core.h to most.h

This patch renames the core header file core.h to most.h. The intention
behind this is to have a meaningful name once this file is moved to the
/include/linux directory.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Link: https://lore.kernel.org/r/1576238662-16512-2-git-send-email-christian.gromm@microchip.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>