SPM: Fix TFM_DEFAULT_SECURE_IRQ_PRIOTITY typo

It should be TFM_DEFAULT_SECURE_IRQ_PRIO*R*ITY.

In the cases when the priority in interrupt controller is not set,
the default value TFM_DEFAULT_SECURE_IRQ_PRIORITY cannot be found
and build fails in IPC model.

Change-Id: I6412de4163c793bfe9da361cacc8e8c19855c76c
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/docs/technical_references/tfm_secure_irq_handling.rst b/docs/technical_references/tfm_secure_irq_handling.rst
index 469d044..253ef35 100644
--- a/docs/technical_references/tfm_secure_irq_handling.rst
+++ b/docs/technical_references/tfm_secure_irq_handling.rst
@@ -80,7 +80,7 @@
   ``signal`` and ``source`` are mandatory.
 
   ``tfm_irq_priority`` is optional. If ``tfm_irq_priority`` is not set for an
-  IRQ, the default is value is ``TFM_DEFAULT_SECURE_IRQ_PRIOTITY``.
+  IRQ, the default is value is ``TFM_DEFAULT_SECURE_IRQ_PRIORITY``.
 
 If an IRQ handler is registered, TF-M will: