Correct typos in comments

The codespell spellchecker tool is used to automatically detect commonly misspelled words in the files of this project.

The misspelled words dictionary was expanded in the latest release of codespell, which resulted in the detection of
misspelled words in the project's comments.

The typos are hereby corrected, which will restore the spell check to a passing state.

Author: per1234

src/Arduino_POSIXStorage.h

@@ -57,7 +57,7 @@
 *********************************************************************************************************
 */
 
-// These are necesssary to expose to the sketch to get the retargeting from mbed -->
+// These are necessary to expose to the sketch to get the retargeting from mbed -->
 
 #if defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_OPTA)
   #include <mbed.h>
@@ -74,7 +74,7 @@
 *********************************************************************************************************
 */
 
-// These are necesssary to expose to the sketch to get the retargeting from mbed -->
+// These are necessary to expose to the sketch to get the retargeting from mbed -->
 
 #if defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_OPTA)
   using mbed::FATFileSystem;