hw/intc: Make rtc variable names consistent

hw/intc: Make rtc variable names consistent

The variables whose values are given by cpu_riscv_read_rtc() should be named
"rtc". The variables whose value are given by cpu_riscv_read_rtc_raw()
should be named "rtc_r".

Signed-off-by: Jason Chien <jason.chien@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20230728082502.26439-2-jason.chien@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit 9382a9eafccad8dc6a487ea3a8d2bed03dc35db9)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>