ida: remove the ida_simple_xxx() API

ida: remove the ida_simple_xxx() API

All users of the ida_simple_xxx() have been converted.  In Linux 6.11-rc2,
the only callers are in tools/testing/.

So it is now time to remove the definition of this old and deprecated
ida_simple_get() and ida_simple_remove().

Link: https://lkml.kernel.org/r/aa205f45fef70a9c948b6a98bad06da58e4de776.1752480043.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>