nvmem: imx-ocotp: set varaiable imx_ocotp_layout storage-class-specifier to static

smatch reports
drivers/nvmem/imx-ocotp.c:599:21: warning: symbol
  'imx_ocotp_layout' was not declared. Should it be static?

This variable is only used in one file so should be static.

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Message-ID: <20230611140330.154222-2-srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>