PCI: designware: Fix RC BAR to be single 64-bit non-prefetchable memory BAR

The Synopsys PCIe core provides one pair of 32-bit BARs (BAR 0 and BAR 1).
The BARs can be configured as follows:

  - One 64-bit BAR: BARs 0 and 1 are combined to form a single 64-bit BAR
  - Two 32-bit BARs: BARs 0 and 1 are two independent 32-bit BARs

This patch corrects 64-bit, non-prefetchable memory BAR configuration
implemented in dw driver.

Signed-off-by: Mohit Kumar <mohit.kumar@st.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Pratyush Anand <pratyush.anand@st.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org	# v3.12+