obs-nvenc: Fix incorrect CUDA array size allocation

[94Bo]

Description

Fix incorrect CUDA array size allocation.

Motivation and Context

The obs-nvenc module was using a double-sized CUDA array as a shared texture with the P010 format.

The original code snippet:

desc.Format = CU_AD_FORMAT_UNSIGNED_INT16;
desc.Height += enc->cy / 2;
desc.NumChannels = 2; // number of bytes per element

According to the cuArray3DCreate documentation,
the previous descriptor requested 4 bytes per element, which was incorrect.

How Has This Been Tested?

The changes were tested on Ubuntu 24.10 with an RTX 3060 Ti GPU.

To force obs-nvenc to use shared textures as if it were running on a different GPU,
in the hevc_nvenc_create function within nvenc.c, nvenc_create_base was called with texture=false.

The frontend configuration used the P010 color format with the NVENC HEVC encoder.

The following recording scenarios were tested:

1. CU_AD_FORMAT_UNSIGNED_INT16 with channels=2 (original): Everything OK
2. CU_AD_FORMAT_UNSIGNED_INT16 with channels=1: Everything OK
3. CU_AD_FORMAT_UNSIGNED_INT8 with channels=2: Everything OK
4. CU_AD_FORMAT_UNSIGNED_INT8 with channels=1: Error occurred.

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[derrod]

This seems fine but please fix the commit message.