RISC-V: defconfigs: Remove redundant CONFIG_EFI=y

We've always had CONFIG_EFI as "def_bool y" so this has always been
redundant.  It's removed by savedefconfig, so drop it to keep things
clean.
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/configs/defconfig

@@ -141,4 +141,3 @@ CONFIG_RCU_EQS_DEBUG=y
 # CONFIG_FTRACE is not set
 # CONFIG_RUNTIME_TESTING_MENU is not set
 CONFIG_MEMTEST=y
-CONFIG_EFI=y