fix: codespell issues

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

src/ffconf_default_32020.h

@@ -143,7 +143,7 @@
 /   1: Enable relative path. f_chdrive() and f_chdir() function are available.
 /   2: f_getcwd() function is available in addition to 1.
 /
-/  Note that output of the f_readdir() fnction is affected by this option. */
+/  Note that output of the f_readdir() function is affected by this option. */
 
 
 /*---------------------------------------------------------------------------/

src/ffconf_default_68300.h

@@ -263,7 +263,7 @@
 #define _NORTC_MON  1
 #define _NORTC_MDAY 1
 #define _NORTC_YEAR 2016
-/* The option _FS_NORTC switches timestamp functiton. If the system does not have
+/* The option _FS_NORTC switches timestamp function. If the system does not have
 /  any RTC function or valid timestamp is not needed, set _FS_NORTC = 1 to disable
 /  the timestamp function. All objects modified by FatFs will have a fixed timestamp
 /  defined by _NORTC_MON, _NORTC_MDAY and _NORTC_YEAR in local time.