drm/panthor: Wait for _READY register when powering on

panthor_gpu_block_power_on() takes a register offset (rdy_reg) for the
purpose of waiting for the power transition to complete. However, a
copy/paste error converting to use the new 64 register functions
switched it to using the pwrtrans_reg register instead. Fix the function
to use the correct register.

Fixes: 4d230aa ("drm/panthor: Add 64-bit and poll register accessors")
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/r/20250630140704.432409-1-steven.price@arm.com

Author: stevenprice-arm

drivers/gpu/drm/panthor/panthor_gpu.c

@@ -297,8 +297,9 @@ int panthor_gpu_block_power_on(struct panthor_device *ptdev,
 
 	gpu_write64(ptdev, pwron_reg, mask);
 
-	ret = gpu_read64_relaxed_poll_timeout(ptdev, pwrtrans_reg, val,
-					      !(mask & val), 100, timeout_us);
+	ret = gpu_read64_relaxed_poll_timeout(ptdev, rdy_reg, val,
+					      (mask & val) == val,
+					      100, timeout_us);
 	if (ret) {
 		drm_err(&ptdev->base, "timeout waiting on %s:%llx readiness",
 			blk_name, mask);