RISC-V: K210 defconfigs: Drop redundant MEMBARRIER=n

As of 93917ad5 ("RISC-V: Add support for restartable sequence") we
have support for restartable sequences, which default to enabled.  These
select MEMBARRIER, so disabling it is now redundant.
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/configs/nommu_k210_defconfig

@@ -21,7 +21,6 @@ CONFIG_CC_OPTIMIZE_FOR_SIZE=y
 # CONFIG_AIO is not set
 # CONFIG_IO_URING is not set
 # CONFIG_ADVISE_SYSCALLS is not set
-# CONFIG_MEMBARRIER is not set
 # CONFIG_KALLSYMS is not set
 CONFIG_EMBEDDED=y
 # CONFIG_VM_EVENT_COUNTERS is not set

arch/riscv/configs/nommu_k210_sdcard_defconfig

@@ -13,7 +13,6 @@ CONFIG_CC_OPTIMIZE_FOR_SIZE=y
 # CONFIG_AIO is not set
 # CONFIG_IO_URING is not set
 # CONFIG_ADVISE_SYSCALLS is not set
-# CONFIG_MEMBARRIER is not set
 # CONFIG_KALLSYMS is not set
 CONFIG_EMBEDDED=y
 # CONFIG_VM_EVENT_COUNTERS is not set

arch/riscv/configs/nommu_virt_defconfig

@@ -19,7 +19,6 @@ CONFIG_EXPERT=y
 # CONFIG_AIO is not set
 # CONFIG_IO_URING is not set
 # CONFIG_ADVISE_SYSCALLS is not set
-# CONFIG_MEMBARRIER is not set
 # CONFIG_KALLSYMS is not set
 # CONFIG_VM_EVENT_COUNTERS is not set
 # CONFIG_COMPAT_BRK is not set