usb: dwc2: Unify flush and reset logic with v4.20a support

usb: dwc2: Unify flush and reset logic with v4.20a support

This patch merges flush and reset logic for both host and gadget code
into a common set of functions, reducing duplication. It also adds support
for the updated reset logic to compatible with core version since v4.20a.

This patch mainly refers to the patch in the kernel.
link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=65dc2e725286106f99c6f6b78e3d9c52c15f3a9c
Signed-off-by: Kongyang Liu <seashell11234455@gmail.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20250110-dwc2-dev-v4-7-987f4fd6f8b2@pigmoral.tech
Signed-off-by: Mattijs Korpershoek <mkorpershoek@kernel.org>