rtc: renesas-rtca3: Fix compilation error on RISC-V

Fix the following compilation errors when building the RTCA3 for RISCV:

../drivers/rtc/rtc-renesas-rtca3.c:270:23: error: call to undeclared function 'FIELD_GET'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  270 |         tm->tm_sec = bcd2bin(FIELD_GET(RTCA3_RSECCNT_SEC, sec));
      |                              ^
../drivers/rtc/rtc-renesas-rtca3.c:369:23: error: call to undeclared function 'FIELD_GET'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  369 |         tm->tm_sec = bcd2bin(FIELD_GET(RTCA3_RSECAR_SEC, sec));
      |                              ^
../drivers/rtc/rtc-renesas-rtca3.c:476:11: error: call to undeclared function 'FIELD_GET'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  476 |         cycles = FIELD_GET(RTCA3_RADJ_ADJ, radj);
      |                  ^
../drivers/rtc/rtc-renesas-rtca3.c:523:9: error: call to undeclared function 'FIELD_PREP'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  523 |         radj = FIELD_PREP(RTCA3_RADJ_ADJ, abs(cycles));
      |                ^
../drivers/rtc/rtc-renesas-rtca3.c:658:8: error: call to undeclared function 'FIELD_PREP'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  658 |         val = FIELD_PREP(RTCA3_RCR1_PES, RTCA3_RCR1_PES_1_64_SEC);
      |               ^

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20241101095720.2247815-5-claudiu.beznea.uj@bp.renesas.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>