nvmem: core: Correct a bunch of function documentations

Correct the documentation for arguments to a number
of functions.

Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>