phy: qcom-qusb2: Fix a memory leak on probe

phy: qcom-qusb2: Fix a memory leak on probe

On success nvmem_cell_read() returns a pointer to a dynamically allocated
buffer, and therefore it shall be freed after usage.

The issue is reported by kmemleak:

  # cat /sys/kernel/debug/kmemleak
  unreferenced object 0xffff3b3803e4b280 (size 128):
    comm "kworker/u16:1", pid 107, jiffies 4294892861 (age 94.120s)
    hex dump (first 32 bytes):
      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    backtrace:
      [<000000007739afdc>] __kmalloc+0x27c/0x41c
      [<0000000071c0fbf8>] nvmem_cell_read+0x40/0xe0
      [<00000000e803ef1f>] qusb2_phy_init+0x258/0x5bc
      [<00000000fc81fcfa>] phy_init+0x70/0x110
      [<00000000e3d48a57>] dwc3_core_soft_reset+0x4c/0x234
      [<0000000027d1dbd4>] dwc3_core_init+0x68/0x990
      [<000000001965faf9>] dwc3_probe+0x4f4/0x730
      [<000000002f7617ca>] platform_probe+0x74/0xf0
      [<00000000a2576cac>] really_probe+0xc4/0x470
      [<00000000bc77f2c5>] __driver_probe_device+0x11c/0x190
      [<00000000130db71f>] driver_probe_device+0x48/0x110
      [<0000000019f36c2b>] __device_attach_driver+0xa4/0x140
      [<00000000e5812ff7>]  bus_for_each_drv+0x84/0xe0
      [<00000000f4bac574>] __device_attach+0xe4/0x1c0
      [<00000000d3beb631>] device_initial_probe+0x20/0x30
      [<000000008019b9db>] bus_probe_device+0xa4/0xb0

Fixes: ca04d9d3e1b1 ("phy: qcom-qusb2: New driver for QUSB2 PHY on Qcom chips")
Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210922233548.2150244-1-vladimir.zapolskiy@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>