configure: correct nvidia configure check to use NVIDIA_CLI consistently

[heasterday]

Addresses #853

Thank you to @jyaghob for the report and the suggested fix.

Tested on an platform with nvidia libraries, diff of before and after the fix below:

diff before.txt after.txt 
46c46
< checking for nVidia libraries & executables... no
---
> checking for nVidia libraries & executables... yes
72d71
< config.status: bin/config.h is unchanged
158c157
<   inject nVidia GPU libraries: no
---
>   inject nVidia GPU libraries: yes
160c159
<     nVidia libraries & executables present ... no
---
>     nVidia libraries & executables present ... yes

[heasterday]

@jyaghob Whenever you have a minute could you verify this fix resolves the issue you are seeing?

[jyaghob]

Yes, thanks. It looks fine for me.