From device data sheet if the silicon version is >='A' then we have the following details.
"By default, ePWM and HRPWM registers are mapped to Peripheral Frame 1 (PF1). Table 6-4 shows this
configuration. To re-map the registers to Peripheral Frame 3 (PF3) to enable DMA access, bit 0 (MAPEPWM) of
MAPCNF register (address 0x702E) must be set to 1. Table 6-5 shows the remapped configuration" of section 6.2.3.
So to use DMA with ePWM module we need to enable the re-map.