kernel: phy: ti: phy-omap-usb2: Fix NULL pointer dereference for SRP

A NULL pointer dereference flaw was found in the Linux kernel in the phy-omap-usb2 driver. This issue arises when the external PHY used with phy-omap-usb2 does not implement the sendsrp function. If this function is called without proper implementation, it can result in a system crash, especially...