x86/resctrl: Export resctrl fs's init function

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T2RT

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/log/?h=mpam/snapshot/v6.7-rc2



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rdtgroup_init() needs exporting so that arch code can call it once
it lives in core code. As this is one of the few functions we export,
rename it to have the filesystems name.

x86's arch code init functions for RDT need renaming (again) to
avoid duplicate definitions.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Zeng Heng <zengheng4@huawei.com>