drivers/fsi: fix fsi_slave_mode prototype

gcc warns about the return type of this function:

drivers/fsi/fsi-core.c:535:8: error: type qualifiers ignored on function return type [-Werror=ignored-qualifiers]

This removes the 'const' attribute, as suggested by the warning.

Fixes: 2b37c3e2 ("drivers/fsi: Set slave SMODE to init communication")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fsi/fsi-core.c

@@ -532,7 +532,7 @@ static inline uint32_t fsi_smode_sid(int x)
 	return (x & FSI_SMODE_SID_MASK) << FSI_SMODE_SID_SHIFT;
 }
 
-static const uint32_t fsi_slave_smode(int id)
+static uint32_t fsi_slave_smode(int id)
 {
 	return FSI_SMODE_WSC | FSI_SMODE_ECRC
 		| fsi_smode_sid(id)