mips: spram: fix missing prototype warning for spram_config

arch/mips/kernel/spram.c:194:6: error: no previous prototype for 'spram_config' [-Werror=missing-prototypes]

Link: https://lkml.kernel.org/r/20231204115710.2247097-15-arnd@kernel.org


Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@rothwell.id.au>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>