misc: ibmasm: fix build errors

Fix build when CONFIG_SERIAL_8250=m and CONFIG_IBM_ASM=y.

Fixes these build errors:

  drivers/built-in.o: In function `ibmasm_remove_one':
  module.c:(.text+0xf6874): undefined reference to `ibmasm_unregister_uart'
  drivers/built-in.o: In function `ibmasm_init_one':
  module.c:(.text+0xf6c37): undefined reference to `ibmasm_register_uart'
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Max Asbock <masbock@us.ibm.com>
Cc: Vernon Mauery <vernux@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/misc/Kconfig

@@ -95,6 +95,7 @@ config DUMMY_IRQ
 config IBM_ASM
 	tristate "Device driver for IBM RSA service processor"
 	depends on X86 && PCI && INPUT
+	depends on SERIAL_8250 || SERIAL_8250=n
 	---help---
 	  This option enables device driver support for in-band access to the
 	  IBM RSA (Condor) service processor in eServer xSeries systems.