media: mali-c55: Fix possible ERR_PTR in enable_streams

media: mali-c55: Fix possible ERR_PTR in enable_streams

The media_pad_remote_pad_unique() function returns either a valid
pointer or an ERR_PTR() on failure (-ENOTUNIQ if multiple links are
enabled, -ENOLINK if no connected pad is found). The return value
was assigned directly to isp->remote_src and dereferenced in the
next line without checking for errors, which could lead to an
ERR_PTR dereference.

Add proper error checking with IS_ERR() before dereferencing the
pointer. Also set isp->remote_src to NULL on error to maintain
consistency with other error paths in the function.

Cc: stable@vger.kernel.org
Fixes: d5f281f3dd29 ("media: mali-c55: Add Mali-C55 ISP driver")
Signed-off-by: Alper Ak <alperyasinak1@gmail.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>