qtnfmac_pcie: rename private Pearl PCIe state structure

In preparation to extract common pcie driver state into a separate
structure, rename Pearl-specific state to qtnf_pcie_pearl_state and move
it directly to pearl-specific PCIe source file.

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>