misc: Remove spear13xx pcie gadget driver

This driver has been marked broken since 2013, see commit 98097858
("misc: mark spear13xx-pcie-gadget as broken"). Let's remove this file
now that it's been more than 5 years of existing in a broken state.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/5d41a2b7.1c69fb81.c8d56.edb6@mx.google.com


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