Remove supports_encryption check from mobile_app (#113490)

helpers already ports nacl at top level so this check can never
be False

```
>>> import sys
>>> from nacl.secret import SecretBox
>>> assert nacl in sys.modules
>>>
```

homeassistant/components/mobile_app/helpers.py

@@ -143,16 +143,6 @@ def error_response(
     )
 
 
-def supports_encryption() -> bool:
-    """Test if we support encryption."""
-    try:
-        import nacl  # noqa: F401 pylint: disable=import-outside-toplevel
-
-        return True
-    except OSError:
-        return False
-
-
 def safe_registration(registration: dict) -> dict:
     """Return a registration without sensitive values."""
     # Sensitive values: webhook_id, secret, cloudhook_url

homeassistant/components/mobile_app/http_api.py

@@ -35,7 +35,6 @@ from .const import (
     DOMAIN,
     SCHEMA_APP_DATA,
 )
-from .helpers import supports_encryption
 from .util import async_create_cloud_hook
 
 
@@ -77,7 +76,7 @@ class RegistrationsView(HomeAssistantView):
 
         data[CONF_WEBHOOK_ID] = webhook_id
 
-        if data[ATTR_SUPPORTS_ENCRYPTION] and supports_encryption():
+        if data[ATTR_SUPPORTS_ENCRYPTION]:
             data[CONF_SECRET] = secrets.token_hex(SecretBox.KEY_SIZE)
 
         data[CONF_USER_ID] = request["hass_user"].id

homeassistant/components/mobile_app/webhook.py

@@ -100,7 +100,6 @@ from .const import (
     DATA_DEVICES,
     DOMAIN,
     ERR_ENCRYPTION_ALREADY_ENABLED,
-    ERR_ENCRYPTION_NOT_AVAILABLE,
     ERR_ENCRYPTION_REQUIRED,
     ERR_INVALID_FORMAT,
     ERR_SENSOR_NOT_REGISTERED,
@@ -115,7 +114,6 @@ from .helpers import (
     error_response,
     registration_context,
     safe_registration,
-    supports_encryption,
     webhook_response,
 )
 
@@ -484,13 +482,6 @@ async def webhook_enable_encryption(
             ERR_ENCRYPTION_ALREADY_ENABLED, "Encryption already enabled"
         )
 
-    if not supports_encryption():
-        _LOGGER.warning(
-            "Unable to enable encryption for %s because libsodium is unavailable!",
-            config_entry.data[ATTR_DEVICE_NAME],
-        )
-        return error_response(ERR_ENCRYPTION_NOT_AVAILABLE, "Encryption is unavailable")
-
     secret = secrets.token_hex(SecretBox.KEY_SIZE)
 
     update_data = {