package/gcc/gcc-initial: fix typo

Fix typo: am internal step -> an internal step

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/gcc/gcc-initial/gcc-initial.mk

@@ -9,7 +9,7 @@ GCC_INITIAL_SITE = $(GCC_SITE)
 GCC_INITIAL_SOURCE = $(GCC_SOURCE)
 
 # We do not have a 'gcc' package per-se; we only have two incarnations,
-# gcc-initial and gcc-final. gcc-initial is just am internal step that
+# gcc-initial and gcc-final. gcc-initial is just an internal step that
 # users should not care about, while gcc-final is the one they shall see.
 HOST_GCC_INITIAL_DL_SUBDIR = gcc