Include <linux/rio_drv.h> for the missing declarations of functions
exported from this file.  Fixes the following sparse warnings:

  drivers/rapidio/rio-access.c:59:1: warning: symbol '__rio_local_read_config_8' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:60:1: warning: symbol '__rio_local_read_config_16' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:61:1: warning: symbol '__rio_local_read_config_32' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:62:1: warning: symbol '__rio_local_write_config_8' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:63:1: warning: symbol '__rio_local_write_config_16' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:64:1: warning: symbol '__rio_local_write_config_32' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:112:1: warning: symbol 'rio_mport_read_config_8' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:113:1: warning: symbol 'rio_mport_read_config_16' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:114:1: warning: symbol 'rio_mport_read_config_32' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:115:1: warning: symbol 'rio_mport_write_config_8' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:116:1: warning: symbol 'rio_mport_write_config_16' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:117:1: warning: symbol 'rio_mport_write_config_32' was not declared. Should it be static?
  drivers/rapidio/rio-access.c:136:5: warning: symbol 'rio_mport_send_doorbell' was not declared. Should it be static?

Link: http://lkml.kernel.org/r/20191017115103.684-1-ben.dooks@codethink.co.ukSigned-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Alexandre Bounine <alex.bou9@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>