video: fbdev: omapfb: Fix set but not used warnings in hdmi*_core

Fix a few W=1 warnings about unused assignments.
Drop the unused error code.

v2:
- Subject updated (Lee)

Signed-off-by: Sam Ravnborg <[e-mail]>
Acked-by: Thomas Zimmermann <[e-mail]>
Cc: Sam Ravnborg <[e-mail]>
Cc: Qilong Zhang <[e-mail]>
Cc: "Alexander A. Klimov" <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Lee Jones <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/omap2/omapfb/dss/hdmi4_core.c

···
 	struct hdmi_audio_format audio_format;
 	struct hdmi_audio_dma audio_dma;
 	struct hdmi_core_audio_config acore;
-	int err, n, cts, channel_count;
+	int n, cts, channel_count;
 	unsigned int fs_nr;
 	bool word_length_16b = false;
 
···
 		return -EINVAL;
 	}
 
-	err = hdmi_compute_acr(pclk, fs_nr, &n, &cts);
+	hdmi_compute_acr(pclk, fs_nr, &n, &cts);
 
 	/* Audio clock regeneration settings */
 	acore.n = n;

drivers/video/fbdev/omap2/omapfb/dss/hdmi5_core.c

···
 	struct hdmi_audio_format audio_format;
 	struct hdmi_audio_dma audio_dma;
 	struct hdmi_core_audio_config core_cfg;
-	int err, n, cts, channel_count;
+	int n, cts, channel_count;
 	unsigned int fs_nr;
 	bool word_length_16b = false;
 
···
 		return -EINVAL;
 	}
 
-	err = hdmi_compute_acr(pclk, fs_nr, &n, &cts);
+	hdmi_compute_acr(pclk, fs_nr, &n, &cts);
 	core_cfg.n = n;
 	core_cfg.cts = cts;