ANDROID: arm64: crypto, LLVMLinux: use %c constraint code in ASM_EXPORT

As suggested at https://llvm.org/bugs/show_bug.cgi?id=27250#c3

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Bug: 32153599
Change-Id: I03d73ee45faf30f70e3c5ee48ee9853617cfc257
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Git-commit: 9ce49358591b044e6731fccdb415173d82d0ed6c
Git-repo: https://android.googlesource.com/kernel/common/


Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>