pinctrl: sh-pfc: r8a7796: Fix GPSR definitions for SDHI2/3

Fix off-by-one (row and/or register) errors in links to Peripheral
Function Select Register bitfields from GPIO/Peripheral Function Select
Register 4 macros for SDHI2 and SDHI3 pins.

Based on rev. 0.52E of the R-Car Gen3 User's Manual.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Simon Horman <horms+renesas@verge.net.au>