README.md: fix link to GPU docs

Remove the space so the link renders properly.

Signed-off-by: Alex Bennée <[email protected]>

Author: stsquad

README.md

@@ -17,7 +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)
+- [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)