Claude review: phy: qualcomm: add MSM8974 HDMI PHY support

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

Adds PLL rate calculation and configuration for the MSM8974 HDMI PHY, building on the preqmp framework from Patch 1 and the UniPHY registers from Patches 2-3.

**Bug: Pixel clock comparison values are in wrong units**

In `qcom_hdmi_msm8974_phy_pll_set_rate()`:
```c
	if (pixclk == 297000) {
		...
	} else if (pixclk == 268500) {
		...
```

`pixclk` is `hdmi_phy->hdmi_opts.tmds_char_rate` which is in Hz (`unsigned long long`). These comparisons against 297000 and 268500 will never be true — the values should be `297000000` (297 MHz) and `268500000` (268.5 MHz), or the code should use `HZ_PER_KHZ` multiplier:
```c
	if (pixclk == 297 * HZ_PER_MHZ) {
```

This also applies to the second comparison at line 7074:
```c
	if (pixclk == 268500)
```

**Minor: Duplicate helpers**

`write16()`, `write24()`, `read24()` are defined again here — same as noted in Patch 1. In this file they could share with the `phy-qcom-hdmi-28lpm.c` definitions via a common header.

**Minor: Unused `div` variable**

In `qcom_28lpm_set_rate()`:
```c
	unsigned int div;
	...
	dev_dbg(hdmi_phy->dev, "rate=%u, div = %d, vco = %lu", pixclk, div, vco_freq);
```

`div` is declared and used in the debug print but never assigned a value in this function. It will contain an indeterminate value.

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Generated by Claude Code Patch Reviewer