staging: most: dim2: replace BUG_ON() in try_start_dim_transfer()

Replace BUG_ON() calls with graceful error handling.

For the null/uninitialized channel checks, return -EINVAL instead of
crashing the kernel. For the zero bus_address check, release the
spinlock and return -EFAULT.

BUG_ON() is deprecated as it crashes the entire kernel on assertion
failure (see Documentation/process/deprecated.rst).

Signed-off-by: Gabriel Rondon <grondon@gmail.com>
Link: https://patch.msgid.link/20260330182255.75241-2-grondon@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: gabrielrondon

drivers/staging/most/dim2/dim2.c

@@ -165,8 +165,8 @@ static int try_start_dim_transfer(struct hdm_channel *hdm_ch)
 	unsigned long flags;
 	struct dim_ch_state st;
 
-	BUG_ON(!hdm_ch);
-	BUG_ON(!hdm_ch->is_initialized);
+	if (!hdm_ch || !hdm_ch->is_initialized)
+		return -EINVAL;
 
 	spin_lock_irqsave(&dim_lock, flags);
 	if (list_empty(head)) {
@@ -187,7 +187,10 @@ static int try_start_dim_transfer(struct hdm_channel *hdm_ch)
 		return -EAGAIN;
 	}
 
-	BUG_ON(mbo->bus_address == 0);
+	if (mbo->bus_address == 0) {
+		spin_unlock_irqrestore(&dim_lock, flags);
+		return -EFAULT;
+	}
 	if (!dim_enqueue_buffer(&hdm_ch->ch, mbo->bus_address, buf_size)) {
 		list_del(head->next);
 		spin_unlock_irqrestore(&dim_lock, flags);