README.md: Update vhost-device-gpu crate README.md link

The crate has been moved from staging to root folder.
Update the README to reflect the correct link for the crate.

Signed-off-by: Dorinda Bassey <[email protected]>

Author: Dorinda Bassey

README.md

@@ -17,6 +17,7 @@ Here is the list of device backends that we support:
 - [CAN](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-can/README.md)
 - [Console](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-console/README.md)
 - [GPIO](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-gpio/README.md)
+- [GPU] (https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-gpu/README.md)
 - [I2C](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-i2c/README.md)
 - [Input](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-input/README.md)
 - [RNG](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-rng/README.md)
@@ -49,7 +50,6 @@ More information may be found in its [README file](./staging/README.md).
 Here is the list of device backends in **staging**:
 
 - [Video](https://github.com/rust-vmm/vhost-device/blob/main/staging/vhost-device-video/README.md)
-- [GPU](https://github.com/rust-vmm/vhost-device/blob/main/staging/vhost-device-gpu/README.md)
 
 <!--
 Template: