fpga: altera-cvp: fix probing for multiple FPGAs on the bus

[ Upstream commit 30522a951f9d02f261d0697c35cb42205b1fae17 ]

Currently registering CvP managers works only for first probed CvP
device, for all other devices it is refused due to duplicated chkcfg
sysfs entry:

fpga_manager fpga3: Altera CvP FPGA Manager @0000:0c:00.0 registered
sysfs: cannot create duplicate filename '/bus/pci/drivers/altera-cvp/chkcfg'
CPU: 0 PID: 3808 Comm: bash Tainted: G           O      4.19.0-custom+ #5
Call Trace:
  dump_stack+0x46/0x5b
  sysfs_warn_dup+0x53/0x60
  sysfs_add_file_mode_ns+0x16d/0x180
  sysfs_create_file_ns+0x51/0x60
  altera_cvp_probe+0x16f/0x2a0 [altera_cvp]
  local_pci_probe+0x3f/0xa0
  ? pci_match_device+0xb1/0xf0
  pci_device_probe+0x116/0x170
  really_probe+0x21b/0x2c0
  driver_probe_device+0x4b/0xe0
  bind_store+0xcb/0x130
  kernfs_fop_write+0xfd/0x180
  __vfs_write+0x21/0x150
  ? selinux_file_permission+0xdc/0x130
  vfs_write+0xa8/0x1a0
  ? find_vma+0xd/0x60
  ksys_write+0x3d/0x90
  do_syscall_64+0x44/0xf0
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  ...
 altera-cvp 0000:0c:00.0: Can't create sysfs chkcfg file
 fpga_manager fpga3: fpga_mgr_unregister Altera CvP FPGA Manager @0000:0c:00.0

Move chkcfg creation to module init as suggested by Alan.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>