x86/sgx: Fix sgx_ioc_enclave_provision() kernel-doc comment

Fix

  ./arch/x86/kernel/cpu/sgx/ioctl.c:666: warning: Function parameter or member \
	  'encl' not described in 'sgx_ioc_enclave_provision'
  ./arch/x86/kernel/cpu/sgx/ioctl.c:666: warning: Excess function parameter \
	  'enclave' description in 'sgx_ioc_enclave_provision'

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201123181922.0c009406@canb.auug.org.au