PCI: pciehp: Simplify Attention Button logging

Previously, pressing the Attention Button always logged two lines, the
first from pciehp_ist() and the second from pciehp_handle_button_press():

  Attention button pressed
  Powering on due to button press

Since pciehp_handle_button_press() always logs the more detailed message,
remove the generic "Attention button pressed" message.  Reword the
pciehp_handle_button_press() to be of the form:

  Button press: will power on in 5 sec
  Button press: will power off in 5 sec
  Button press: canceling request to power on
  Button press: canceling request to power off
  Button press: ignoring invalid state %#x

Link: https://lore.kernel.org/r/20230522214051.619337-1-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>