[SPARC64]: Don't include drivers/firmware/Kconfig

It's really not relevant for this platform in any
way, after all.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc64/Kconfig

@@ -178,8 +178,6 @@ endchoice
 
 endmenu
 
-source "drivers/firmware/Kconfig"
-
 source "mm/Kconfig"
 
 config GENERIC_ISA_DMA