nvme: Remove the redundant aqa value setting

AQA (Admin Queue Attributes) register is a dword size with
lower word of ASQS, and higher word of ACQS.

The code set the variable aqa twice, but it is redundant.

Signed-off-by: Wesley Sheng <wesleyshenggit@sina.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>