S390: Add PCI_MIO and SIE HWCAPs

Both new HWCAPs were introduced in these kernel commits:
- 7e8403ecaf884f307b627f3c371475913dd29292
  "s390: add HWCAP_S390_PCI_MIO to ELF hwcaps"
- 7e82523f2583e9813e4109df3656707162541297
  "s390/hwcaps: make sie capability regular hwcap"

Also note that the kernel commit 511ad531afd4090625def4d9aba1f5227bd44b8e
"s390/hwcaps: shorten HWCAP defines" has shortened the prefix of the macros
from "HWCAP_S390_" to "HWCAP_".  For compatibility reasons, we do not
change the prefix in public glibc header file.