Documentation: irqdomain: Fix typo of "at least once"

Signed-off-by: NEric Lin <dslin1010@gmail.com>
Link: https://lore.kernel.org/r/20220811091516.2107908-1-dslin1010@gmail.comSigned-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/core-api/irq/irq-domain.rst

@@ -71,7 +71,7 @@ variety of methods:
 Note that irq domain lookups must happen in contexts that are
 compatible with a RCU read-side critical section.
 
-The irq_create_mapping() function must be called *atleast once*
+The irq_create_mapping() function must be called *at least once*
 before any call to irq_find_mapping(), lest the descriptor will not
 be allocated.