fbtft: Update REAMDE to slow down the stream of undesired cleanups

fbtft: Update REAMDE to slow down the stream of undesired cleanups

Lately the enormous amount of some untested cleanups started coming
to a mailing list. This adds an unneeded and undesired burden on
the reviewers and maintainers. Try to stop that by clearly state
what we accept and on what conditions in the README file.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260226080845.4081732-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>