[MIPS] Sibyte: Remove broken dependency on EXPERIMENTAL from SIBYTE_SB1xxx_SOC.

Otherwise Kconfig will produce a nonsenical .config for a kernel that is
neither 32-bit nor 64-bit.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/sibyte/Kconfig

@@ -48,7 +48,6 @@ config SIBYTE_BCM1x55
 
 config SIBYTE_SB1xxx_SOC
 	bool
-	depends on EXPERIMENTAL
 	select DMA_COHERENT
 	select SIBYTE_CFE
 	select SWAP_IO_SPACE