AM3352 RTC without PMIC_POWER_EN function

AM335X Datasheet, section 4.1.1 shows Power-Up Sequencing.  The PWRONRSTn signal can be used for  and RTC_PWRONRSTn, but it must be a 1.8V level signal, because RTC_PWRONRSTn is in VDDS_RTC power domain. VDDS_RTC can be ramped up independently from the other power supply, but if VDDS_RTC is ramped after VDD_CORE, there might be a small amount of additional leakage current on VDD_CORE (see Note E below Figure 4-1). You may supply VDDS_RTC and VDDS_DDR from the same 1.8V source (if you use DDR3 this won't be possible, because DDR3 works at 1.5V). But you should be aware of possible noise issues from the DDR circuitry.

1.1V VDD_CORE for CAP_VDD_RTC works only when RTC_KALDO_ENn is pulled up to 1.8V. If you have 1.8V present on the board all the time you need the RTC, and if you don't plan to change VDD_CORE voltage during operation (different OPP's), then there is no problem to keep the same configuration.