staging: m57621-mmc: delete driver from the tree.

[ Upstream commit 441bf7332d55c4d34afae9ffc3bbec621093f4d1 ]

The license text in this driver is "interesting" and not really obvious
that it is supposed to be able to be distributed in the kernel source
tree.  Yes, the MODULE_LICENSE() text says GPL, so it's probably ok, but
to be safe, I am deleting this driver.  I will be glad to add it back if
the license is properly sorted out, but for now, this isn't worth the
potential risk, I should have never taken it in the first place.

Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: NeilBrown <neil@brown.name>
Cc: George Hilliard <thirtythreeforty@gmail.com>
Cc: "Christian Lütke-Stetzkamp" <christian@lkamp.de>
Cc: Nishad Kamdar <nishadkamdar@gmail.com>
Cc: Sergej Perschin <ser.perschin@gmail.com>
Cc: John Crispin <blogic@openwrt.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>