ARM: OMAP2+: pmic-cpcap: fix kernel-doc warnings

Use the correct function names in kernel-doc comments.
Use "Return[s]:" kernel-doc notation for function return values.

These changes prevent the following warnings:

pmic-cpcap.c:28: warning: expecting prototype for omap_cpcap_vsel_to_vdc(). Prototype was for omap_cpcap_vsel_to_uv() instead
pmic-cpcap.c:92: warning: expecting prototype for omap_max8952_vsel_to_vdc(). Prototype was for omap_max8952_vsel_to_uv() instead
pmic-cpcap.c:139: warning: expecting prototype for omap_fan5355_vsel_to_vdc(). Prototype was for omap_fan535503_vsel_to_uv() instead
pmic-cpcap.c:154: warning: expecting prototype for omap_fan535508_vsel_to_vdc(). Prototype was for omap_fan535508_vsel_to_uv() instead
pmic-cpcap.c:28: warning: No description found for return value of 'omap_cpcap_vsel_to_uv'
pmic-cpcap.c:42: warning: No description found for return value of 'omap_cpcap_uv_to_vsel'
pmic-cpcap.c:92: warning: No description found for return value of 'omap_max8952_vsel_to_uv'
pmic-cpcap.c:106: warning: No description found for return value of 'omap_max8952_uv_to_vsel'
pmic-cpcap.c:139: warning: No description found for return value of 'omap_fan535503_vsel_to_uv'
pmic-cpcap.c:154: warning: No description found for return value of 'omap_fan535508_vsel_to_uv'
pmic-cpcap.c:172: warning: No description found for return value of 'omap_fan535503_uv_to_vsel'
pmic-cpcap.c:191: warning: No description found for return value of 'omap_fan535508_uv_to_vsel'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: linux-omap@vger.kernel.org
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: patches@armlinux.org.uk
Message-ID: <20240117011004.22669-9-rdunlap@infradead.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>