power: supply: core: fix static checker warning

static checker complains, that the block already breaks if IS_ERR(np)
and thus the extra !IS_ERR(np) check in the while condition is
superfluous. Avoid the extra check by using while(true) instead. This
should not change the runtime behavior at all and I expect the binary
to be more or less the same for an optimizing compiler.

Fixes: f368f87b22da ("power: supply: core: convert to fwnnode")
Reported-by: Dan Carpenter <[e-mail]>
Closes: https://lore.kernel.org/linux-pm/[e-mail]/
Reviewed-by: Hans de Goede <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/supply/power_supply_core.c

···
 			break;
 		}
 		fwnode_handle_put(np);
-	} while (!IS_ERR(np));
+	} while (true);
 
 	return 0;
 }