selftests/sgx: Remove redundant enclave base address save/restore

Remove redundant push/pop pair that stores and restores the enclave base
address in the test enclave, as it is never used after the pop and can
anyway be easily retrieved via the __encl_base symbol.
Signed-off-by: Jo Van Bulck <jo.vanbulck@cs.kuleuven.be>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/all/20231005153854.25566-7-jo.vanbulck%40cs.kuleuven.be

tools/testing/selftests/sgx/test_encl_bootstrap.S

@@ -55,12 +55,9 @@ encl_entry_core:
 	push	%rax
 
 	push	%rcx # push the address after EENTER
-	push	%rbx # push the enclave base address
 
 	call	encl_body
 
-	pop	%rbx # pop the enclave base address
-
 	/* Clear volatile GPRs, except RAX (EEXIT function). */
 	xor     %rcx, %rcx
 	xor     %rdx, %rdx