xen/arm: optee: Fix arm_smccc_smc's a0 for OPTEE_SMC_DISABLE_SHM_CACHE

xen/arm: optee: Fix arm_smccc_smc's a0 for OPTEE_SMC_DISABLE_SHM_CACHE

Fix a possible copy-paste error in arm_smccc_smc's first argument (a0)
for OPTEE_SMC_DISABLE_SHM_CACHE case.

This error causes Linux > v5.14-rc5 (b5c10dd04b7418793517e3286cde5c04759a86de
optee: Clear stale cache entries during initialization) to stuck
repeatedly issuing OPTEE_SMC_DISABLE_SHM_CACHE call and waiting for
the result to be OPTEE_SMC_RETURN_ENOTAVAIL which will never happen.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Fixes: 2e35cdf9b2ca ("xen/arm: optee: add OP-TEE mediator skeleton")
Backport: 4.13+