x86/sgx: Export sgx_encl_page_alloc()

mainline inclusion
from mainline-6.0-rc1
commit 8123073c
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5USAM


CVE: NA

Intel-SIG: commit 8123073c x86/sgx: Export sgx_encl_page_alloc().
Backport for SGX EDMM support.

--------------------------------

Move sgx_encl_page_alloc() to encl.c and export it so that it can be
used in the implementation for support of adding pages to initialized
enclaves, which requires to allocate new enclave pages.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/57ae71b4ea17998467670232e12d6617b95c6811.1652137848.git.reinette.chatre@intel.com


Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>