ppc/pnv: use stack->pci_regs[] in pnv_pec_stk_pci_xscom_write()

ppc/pnv: use stack->pci_regs[] in pnv_pec_stk_pci_xscom_write()

pnv_pec_stk_pci_xscom_write() is pnv_pec_stk_pci_xscom_ops write
callback. It writes values into regs in the stack->nest_regs[] array.
The pnv_pec_stk_pci_xscom_read read callback, on the other hand, returns
values of the stack->pci_regs[]. In fact, at this moment, the only use
of stack->pci_regs[] is in pnv_pec_stk_pci_xscom_read(). There's no code
that is written anything in stack->pci_regs[], which is suspicious.

Considering that stack->nest_regs[] is widely used by the nested
MemoryOps pnv_pec_stk_nest_xscom_ops, in both read and write callbacks,
the conclusion is that we're writing the wrong array in
pnv_pec_stk_pci_xscom_write(). This function should write stack->pci_regs[]
instead.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Message-Id: <20220111200132.633896-2-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>