Fix metadirective_arch_*.F90: var init; condition

[tob2]

• tests/5.0/metadirective/test_metadirective_arch_is_nvidia.F90: Fix index for on-device initialization.
• tests/5.0/metadirective/test_metadirective_arch_nvidia_or_amd.F90: Fix condition: it was reverse.

@spophale @nolanbaker31 @seyonglee @fel-cab — Please review.

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_With error checking macros including C's assert, I always confused whether the positive or negative condition should be used. Seemingly, I am not alone. When I add a print *, 'initial_device', initial_device after the big WHILE loop, I get (w/o the patch):_

 initial_device F
[OMPVV_ERROR test_metadirective_arch_nvidia_or_amd.F90:57]  Condition  .NOT. initial_device failed
[OMPVV_ERROR test_metadirective_arch_nvidia_or_amd.F90:58] NVIDIA and AMD architecture not available, ran on host

[tob2]

@spophale @nolanbaker31 @seyonglee @fel-cab — Ping, please review.

[tob2]

@spophale @nolanbaker31 @seyonglee @fel-cab — Ping, please review.