drm/vc4: hdmi: Replace hardcoded value by define

The 120MHz value hardcoded in the call to max_t to compute the HSM rate
is defined in the driver as HSM_MIN_CLOCK_FREQ, let's switch to it so
that it's more readable.
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20230126-rpi-display-fw-clk-cleanup-v1-1-d646ff6fb842@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -1482,7 +1482,9 @@ static void vc4_hdmi_encoder_pre_crtc_configure(struct drm_encoder *encoder,
 	 * Additionally, the AXI clock needs to be at least 25% of
 	 * pixel clock, but HSM ends up being the limiting factor.
 	 */
-	hsm_rate = max_t(unsigned long, 120000000, (tmds_char_rate / 100) * 101);
+	hsm_rate = max_t(unsigned long,
+			 HSM_MIN_CLOCK_FREQ,
+			 (tmds_char_rate / 100) * 101);
 	ret = clk_set_min_rate(vc4_hdmi->hsm_clock, hsm_rate);
 	if (ret) {
 		DRM_ERROR("Failed to set HSM clock rate: %d\n", ret);