Modify USBD_DEFINE_MSC_LUN() to take in separate id by which the LUNs
are sorted. Previously the disk name itself was implicitly used as a
sorting key. This is a breaking change to Experimental API.
Another advantage of splitting the sorting id from disk name is the
ability to use KConfig symbols as disk name. Currently the MMC disk
driver uses KConfig symbol CONFIG_MMC_VOLUME_NAME.
Mark LUN definitions as static const because the LUNs are ending up in
ITERABLE_SECTION_ROM().
Signed-off-by: Tomasz Moń <tomasz.mon@nordicsemi.no>
aa6319dcfd