psci: Do not define do_poweroff() if CONFIG_SYSRESET_CMD_POWEROFF is enabled

CONFIG_SYSRESET_CMD_POWEROFF defines do_poweroff() in sysreset-uclass.c
that's why don't define it twice when both CONFIG_SYSRESET_CMD_POWEROFF and
CONFIG_CMD_POWEROFF are enabled. CONFIG_SYSRESET_CMD_POWEROFF depends on
CONFIG_CMD_POWEROFF.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

drivers/firmware/psci.c

@@ -210,7 +210,7 @@ void psci_sys_poweroff(void)
 	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
 }
 
-#ifdef CONFIG_CMD_POWEROFF
+#if IS_ENABLED(CONFIG_CMD_POWEROFF) && !IS_ENABLED(CONFIG_SYSRESET_CMD_POWEROFF)
 int do_poweroff(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 {
 	do_psci_probe();