[PowerPC64] Don't mark module data as static

[PowerPC64] Don't mark module data as static

Fixes panic when loading ipfw.ko and if_epair.ko built with modern compiler.

Similar to arm64 and riscv, when using a modern compiler (!gcc4.2), code
generated tries to access data in the wrong location, causing kernel panic
(data storage interrupt trap) when loading if_epair and ipfw.

Issue was reproduced with kernel/module compiled using gcc8 and clang8. It
affects both ELFv1 and ELFv2 ABI environments.

PR:		232387
Submitted by:	alfredo.junior_eldorado.org.br
Reported by:	Mark Millard
Reviewed by:	jhibbits
Differential Revision:	https://reviews.freebsd.org/D20461