PCI: endpoint: Remove unused field in struct pci_epf_group

PCI: endpoint: Remove unused field in struct pci_epf_group

In "struct pci_epf_group", the 'type_group' field is unused.

This was added, but already unused, by commit 70b3740f2c19 ("PCI: endpoint:
Automatically create a function specific attributes group").

Thus, remove it.

Found with cppcheck, unusedStructMember.

[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/6507d44b6c60a19af35a605e2d58050be8872ab6.1712341008.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>