Add MI300 details to docs

[peterjunpark]

This PR updates the documentation with info about the MI300 series

Performance model

L1

• Update L1 cache line size to 128B for MI300 (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/vector-l1-cache.html#l1-cache-line-size) (64B for MI200).

UTCL1

• Update UTCL1 hit-on-miss note to specify MI200 because it doesn't apply to MI300 (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/vector-l1-cache.html#l1-unified-translation-cache-utcl1).

L2

• Update L2 cache line size to 128B for MI300 (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/l2-cache.html#l2-cache-line-size) (128B for MI300 and MI200).

• Update channel count in text for MI300 (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/l2-cache.html#l2-cache-tcc)

• Atomic requests (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/l2-cache.html#request-flow)

• Add 128B read request metric to table (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/l2-cache.html#detailed-transaction-metrics)

VALU

= Add MI300 to list of products with MFMA units (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/pipeline-descriptions.html#vector-arithmetic-logic-unit-valu)

AGPRs

• Add MI300 to list here (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/pipeline-descriptions.html#accumulation-vector-general-purpose-registers-agprs) (512 KB based on https://rocm.docs.amd.com/en/latest/reference/gpu-arch-specs.html)

Scalar / Instruction cache

• 64KB / shared between 2CUs on MI300 (https://advanced-micro-devices-demo--446.com.readthedocs.build/projects/rocprofiler-compute/en/446/conceptual/shader-engine.html#scalar-l1-data-cache-sl1d)