docs: replace clock_gettime

the time() implementation now uses
sys_clock_gettime(), change that in the docs.

Signed-off-by: Fin Maaß <f.maass@vogl-electronic.com>

Author: maass-hamburg

doc/develop/languages/c/common_libc.rst

@@ -12,7 +12,7 @@ Time function
 *************
 
 This provides an implementation of the standard C function, :c:func:`time`,
-relying on the Zephyr function, :c:func:`clock_gettime`. This function can
+relying on the Zephyr function, :c:func:`sys_clock_gettime`. This function can
 be enabled by selecting :kconfig:option:`COMMON_LIBC_TIME`.
 
 Dynamic Memory Management