m68k: migrate to kernel 5.4.x

target/config/Config.in.compiler

@@ -20,6 +20,7 @@ default ADK_TOOLCHAIN_GCC_METAG if ADK_TARGET_ARCH_METAG
 default ADK_TOOLCHAIN_GCC_NDS32 if ADK_TARGET_ARCH_NDS32
 default ADK_TOOLCHAIN_GCC_7 if ADK_TARGET_CPU_ARM_ARM11MPCORE
 default ADK_TOOLCHAIN_GCC_7 if ADK_TARGET_CPU_ARM_CORTEX_A53
+default ADK_TOOLCHAIN_GCC_7 if ADK_TARGET_ARCH_M68K
 default ADK_TOOLCHAIN_GCC_7 if ADK_TARGET_ARCH_SPARC
 default ADK_TOOLCHAIN_GCC_9 if ADK_TARGET_ARCH_CSKY
 default ADK_TOOLCHAIN_GCC_9 if ADK_TARGET_ARCH_HPPA

target/linux/Config.in.kernelversion

@@ -25,6 +25,7 @@ default ADK_TARGET_LINUX_KERNEL_VERSION_4_9 if ADK_TARGET_CPU_ARM_ARM11MPCORE
 default ADK_TARGET_LINUX_KERNEL_VERSION_4_9 if ADK_TARGET_CPU_ARM_CORTEX_A53
 default ADK_TARGET_LINUX_KERNEL_VERSION_4_14 if ADK_TARGET_SYSTEM_QEMU_ARM_VERSATILEPB
 default ADK_TARGET_LINUX_KERNEL_VERSION_5_4 if ADK_TARGET_ARCH_CSKY
+default ADK_TARGET_LINUX_KERNEL_VERSION_5_4 if ADK_TARGET_ARCH_M68K
 default ADK_TARGET_LINUX_KERNEL_VERSION_5_4 if ADK_TARGET_ARCH_RISCV32
 default ADK_TARGET_LINUX_KERNEL_VERSION_5_4 if ADK_TARGET_ARCH_RISCV64
 default ADK_TARGET_LINUX_KERNEL_VERSION_5_4 if ADK_TARGET_ARCH_OR1K