IMSM - allow assembling any imsm array even without OROM.

IMSM - allow assembling any imsm array even without OROM.

It is important to check for compatibility with 'platform' or
Option ROM when creating or changing and array.  However there is no
real need when simply assembling the array.

On some systems there are situations where the platform information is
not available.  e.g. on some UEFI systems, UEFI is not available
during 'kdump' handling.  This makes it impossible to assemble
an IMSM array to receive the dump.

So remove the requirements that the platform be visible to assemble
an IMSM array.

Signed-off-by: NeilBrown <neilb@suse.de>