regulator: cpcap-regulator: Demote kerneldoc header to standard comment

Nothing about this comment identifies it as a kerneldoc header.
They're missing all of their struct's property descriptions and
the correct 'struct *' header.

Fixes the following W=1 warning(s):

 drivers/regulator/cpcap-regulator.c:99: warning: cannot understand function prototype: 'struct cpcap_regulator '
 drivers/regulator/cpcap-regulator.c:337: warning: cannot understand function prototype: 'const struct cpcap_regulator omap4_regulators[] = '

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200625163614.4001403-9-lee.jones@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>