optee: add RPMB dependency

Prevent build error when CONFIG_RPMB=m and CONFIG_OPTEE=y by adding a
dependency to CONFIG_RPMB for CONFIG_OPTEE so the RPMB subsystem always
is reachable if configured. This means that CONFIG_OPTEE automatically
becomes compiled as a module if CONFIG_RPMB is compiled as a module. If
CONFIG_RPMB isn't configured or is configured as built-in, CONFIG_OPTEE
will remain unchanged.

Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Fixes: f0c8431568ee ("optee: probe RPMB device using RPMB subsystem")
Signed-off-by: Jens Wiklander <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/tee/optee/Kconfig

···
 	tristate "OP-TEE"
 	depends on HAVE_ARM_SMCCC
 	depends on MMU
+	depends on RPMB || !RPMB
 	help
 	  This implements the OP-TEE Trusted Execution Environment (TEE)
 	  driver.