bsps/*acpi*: Address unterminated string warnings

The ACPI source has multiple tables where a Name field is defined.
The name field is a character array with a length of 4. All of the
string initializers are four characters plus a NUL. The code is
careful to use strn*() functions and intentionally avoids assuming
there is space for the NUL. With lots of entries in the various
arrays, this was clearly a design decision to save space.

This was caught by GCC's -Wunterminated-string-initialization
warning. The solution used is to use the "nonstring" attribute
recommended by the GCC manual.

Closes #5329

bsps/shared/acpi/acpica/namespace/nsrepair2.c

@@ -169,6 +169,9 @@ ACPI_STATUS (*ACPI_REPAIR_FUNCTION) (
 
 typedef struct acpi_repair_info
 {
+#ifdef __rtems__
+    __attribute__ ((nonstring))
+#endif /* rtems */
     char                    Name[ACPI_NAMESEG_SIZE];
     ACPI_REPAIR_FUNCTION    RepairFunction;