ARM: pxa: remove use of symbol_get()

ARM: pxa: remove use of symbol_get()

The spitz board file uses the obscure symbol_get() function
to optionally call a function from sharpsl_pm.c if that is
built. However, the two files are always built together
these days, and have been for a long time, so this can
be changed to a normal function call.

Link: https://lore.kernel.org/lkml/20230731162639.GA9441@lst.de/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>