[PATCH] arc: include: asm: define empty SERIAL_PORT_DFNS in serial.h

[Chen Gang <gang.chen@asianux.com>]

For some architectures (e.g. arc, openrisc), BASE_BAUD isn't constant
And SERIAL_PORT_DFNS always use BASE_BAUND, and also all drivers use
SERIAL_PORT_DFNS to initialize static variables, statically.

So need define SERIAL_PORT_DFNS as empty to tell drivers they don't
support SERIAL_PORT_DFNS (mostly like frv and parisc did), or can not
pass compiling

The related error (allmodconfig for arc with gcc-4.8.0):

    CC [M]  drivers/staging/speakup/serialio.o
  drivers/staging/speakup/serialio.c:12:2: error: initializer element is not constant
    SERIAL_PORT_DFNS
    ^
  drivers/staging/speakup/serialio.c:12:2: error: (near initialization for 'rs_table[0].baud_base')
  drivers/staging/speakup/serialio.c:12:2: error: initializer element is not constant
  drivers/staging/speakup/serialio.c:12:2: error: (near initialization for 'rs_table[1].baud_base')
  drivers/staging/speakup/serialio.c:12:2: error: initializer element is not constant
  drivers/staging/speakup/serialio.c:12:2: error: (near initialization for 'rs_table[2].baud_base')
  drivers/staging/speakup/serialio.c:12:2: error: initializer element is not constant
  drivers/staging/speakup/serialio.c:12:2: error: (near initialization for 'rs_table[3].baud_base')


Signed-off-by: Chen Gang <gang.chen@asianux.com>
---
 arch/arc/include/asm/serial.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/arc/include/asm/serial.h b/arch/arc/include/asm/serial.h
index 602b097..f18b772 100644
--- a/arch/arc/include/asm/serial.h
+++ b/arch/arc/include/asm/serial.h
@@ -32,4 +32,6 @@
 #define BASE_BAUD	(arc_get_core_freq() / 16 / 3)
 #endif
 
+#define			SERIAL_PORT_DFNS
+
 #endif /* _ASM_ARC_SERIAL_H */
-- 
1.7.7.6