x86_64: unbreak squashfs images

Enable the required squashfs and block2mtd support in the kernel in order
to be able to actually boot them.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

SVN-Revision: 42967

target/linux/x86_64/config-default

@@ -315,7 +315,11 @@ CONFIG_MFD_CORE=y
 # CONFIG_MLX5_CORE is not set
 CONFIG_MODULES_USE_ELF_RELA=y
 # CONFIG_MPSC is not set
-# CONFIG_MTD is not set
+CONFIG_MTD_BLOCK2MTD=y
+# CONFIG_MTD_NETSC520 is not set
+# CONFIG_MTD_SBC_GXX is not set
+# CONFIG_MTD_SC520CDP is not set
+# CONFIG_MTD_TS5500 is not set
 CONFIG_MTRR=y
 # CONFIG_MTRR_SANITIZER is not set
 CONFIG_NAMESPACES=y
@@ -396,7 +400,6 @@ CONFIG_SPARSEMEM_MANUAL=y
 # CONFIG_SPARSEMEM_VMEMMAP is not set
 CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y
 CONFIG_SPARSE_IRQ=y
-# CONFIG_SQUASHFS is not set
 CONFIG_STRICT_DEVMEM=y
 CONFIG_SWIOTLB=y
 CONFIG_SYSCTL_EXCEPTION_TRACE=y