drivers: flash: shell: Add support for devices without erase

Shell will now work with devices that do not implement erase callback.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

drivers/flash/flash_shell.c

@@ -75,9 +75,10 @@ static int cmd_erase(const struct shell *sh, size_t argc, char *argv[])
 {
  const struct device *flash_dev;
  uint32_t page_addr;
- int result;
+ int result = -ENOTSUP;
  uint32_t size;
 
+#if defined(CONFIG_FLASH_HAS_EXPLICIT_ERASE)
  result = parse_helper(sh, &argc, &argv, &flash_dev, &page_addr);
  if (result) {
  return result;
@@ -106,6 +107,7 @@ static int cmd_erase(const struct shell *sh, size_t argc, char *argv[])
  } else {
  shell_print(sh, "Erase success.");
  }
+#endif
 
  return result;
 }