bus: brcmstb_gisb: correct support for 64-bit address output

The GISB bus can support addresses beyond 32-bits.  So this commit
corrects support for reading a captured 64-bit address into a 64-bit
variable by obtaining the high bits from the ARB_ERR_CAP_HI_ADDR
register (when present) and then outputting the full 64-bit value.

It also removes unused definitions.

Fixes: 44127b77 ("bus: add Broadcom GISB bus arbiter timeout/error handler")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Gregory Fong <gregory.0xf0@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>