nvmem: sunplus-ocotp: staticize sp_otp_v0

The "sp_otp_v0" file scope variable is not used outside, so make it
static to fix warning:

  drivers/nvmem/sunplus-ocotp.c:74:29: sparse:
    sparse: symbol 'sp_otp_v0' was not declared. Should it be static?
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20220321110326.44652-2-krzk@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/sunplus-ocotp.c

@@ -71,7 +71,7 @@ struct sp_ocotp_data {
 	int size;
 };
 
-const struct sp_ocotp_data  sp_otp_v0 = {
+static const struct sp_ocotp_data sp_otp_v0 = {
 	.size = QAC628_OTP_SIZE,
 };