net: mana: Guard mana_remove against double invocation

net: mana: Guard mana_remove against double invocation

If PM resume fails (e.g., mana_attach() returns an error), mana_probe()
calls mana_remove(), which tears down the device and sets
gd->gdma_context = NULL and gd->driver_data = NULL.

However, a failed resume callback does not automatically unbind the
driver. When the device is eventually unbound, mana_remove() is invoked
a second time. Without a NULL check, it dereferences gc->dev with
gc == NULL, causing a kernel panic.

Add an early return if gdma_context or driver_data is NULL so the second
invocation is harmless. Move the dev = gc->dev assignment after the
guard so it cannot dereference NULL.

Fixes: 635096a86edb ("net: mana: Support hibernation and kexec")
Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
Link: https://patch.msgid.link/20260420124741.1056179-4-ernis@linux.microsoft.com
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>