PowerPC: Fix typo in PowerPC note pseudo-section names

PowerPC: Fix typo in PowerPC note pseudo-section names

The recent tidy-up commit 09e56f0515c3 ("Code tidy: bfd/elf.c:
Tidy up core note handling code.") introduced regressions in the
PowerPC core note handling.  The pseudo-section names for TM_CVSX,
TM_SPR, VSX and VMX notes were defined with an underscore instead of a
hyphen, breaking GDB test cases.  The same goes for one riscv and one
s390 define.

This patch restores the correct section names by using hyphens in the
definitions, fixing 897 GDB test failures on PowerPC.

bfd/
	* elf.c: (NOTE_PSEUDO_SECTION_PPC_TM_CVSX),
	(NOTE_PSEUDO_SECTION_PPC_TM_SPR, NOTE_PSEUDO_SECTION_PPC_VSX),
	(NOTE_PSEUDO_SECTION_PPC_VMX, NOTE_PSEUDO_SECTION_RISCV_CSR),
	(NOTE_PSEUDO_SECTION_S390_CTRS): Use hyphens in section names
	instead of underscores.