misc: rtsx: remove unused function

removed unused function 'rtsx_pci_disable_aspm'

Signed-off-by: Ricky Wu <ricky_wu@realtek.com>
Link: https://lore.kernel.org/r/20201230063953.10972-1-ricky_wu@realtek.com


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